1 /*
2 * Copyright 1997-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Portions of code courtesy of Clifford Click
26
27 // Optimization - Graph Style
28
29 #include "incls/_precompiled.incl"
30 #include "incls/_cfgnode.cpp.incl"
31
32 //=============================================================================
33 //------------------------------Value------------------------------------------
34 // Compute the type of the RegionNode.
35 const Type *RegionNode::Value( PhaseTransform *phase ) const {
36 for( uint i=1; i<req(); ++i ) { // For all paths in
37 Node *n = in(i); // Get Control source
38 if( !n ) continue; // Missing inputs are TOP
39 if( phase->type(n) == Type::CONTROL )
40 return Type::CONTROL;
41 }
42 return Type::TOP; // All paths dead? Then so are we
43 }
44
45 //------------------------------Identity---------------------------------------
46 // Check for Region being Identity.
47 Node *RegionNode::Identity( PhaseTransform *phase ) {
48 // Cannot have Region be an identity, even if it has only 1 input.
49 // Phi users cannot have their Region input folded away for them,
50 // since they need to select the proper data input
51 return this;
52 }
53
54 //------------------------------merge_region-----------------------------------
55 // If a Region flows into a Region, merge into one big happy merge. This is
56 // hard to do if there is stuff that has to happen
57 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
58 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
59 return NULL;
60 Node *progress = NULL; // Progress flag
61 PhaseIterGVN *igvn = phase->is_IterGVN();
62
63 uint rreq = region->req();
64 for( uint i = 1; i < rreq; i++ ) {
65 Node *r = region->in(i);
66 if( r && r->Opcode() == Op_Region && // Found a region?
67 r->in(0) == r && // Not already collapsed?
68 r != region && // Avoid stupid situations
69 r->outcnt() == 2 ) { // Self user and 'region' user only?
70 assert(!r->as_Region()->has_phi(), "no phi users");
71 if( !progress ) { // No progress
72 if (region->has_phi()) {
73 return NULL; // Only flatten if no Phi users
74 // igvn->hash_delete( phi );
75 }
76 igvn->hash_delete( region );
77 progress = region; // Making progress
78 }
79 igvn->hash_delete( r );
80
81 // Append inputs to 'r' onto 'region'
82 for( uint j = 1; j < r->req(); j++ ) {
83 // Move an input from 'r' to 'region'
84 region->add_req(r->in(j));
85 r->set_req(j, phase->C->top());
86 // Update phis of 'region'
87 //for( uint k = 0; k < max; k++ ) {
88 // Node *phi = region->out(k);
89 // if( phi->is_Phi() ) {
90 // phi->add_req(phi->in(i));
91 // }
92 //}
93
94 rreq++; // One more input to Region
95 } // Found a region to merge into Region
96 // Clobber pointer to the now dead 'r'
97 region->set_req(i, phase->C->top());
98 }
99 }
100
101 return progress;
102 }
103
104
105
106 //--------------------------------has_phi--------------------------------------
107 // Helper function: Return any PhiNode that uses this region or NULL
108 PhiNode* RegionNode::has_phi() const {
109 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
110 Node* phi = fast_out(i);
111 if (phi->is_Phi()) { // Check for Phi users
112 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
113 return phi->as_Phi(); // this one is good enough
114 }
115 }
116
117 return NULL;
118 }
119
120
121 //-----------------------------has_unique_phi----------------------------------
122 // Helper function: Return the only PhiNode that uses this region or NULL
123 PhiNode* RegionNode::has_unique_phi() const {
124 // Check that only one use is a Phi
125 PhiNode* only_phi = NULL;
126 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
127 Node* phi = fast_out(i);
128 if (phi->is_Phi()) { // Check for Phi users
129 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
130 if (only_phi == NULL) {
131 only_phi = phi->as_Phi();
132 } else {
133 return NULL; // multiple phis
134 }
135 }
136 }
137
138 return only_phi;
139 }
140
141
142 //------------------------------check_phi_clipping-----------------------------
143 // Helper function for RegionNode's identification of FP clipping
144 // Check inputs to the Phi
145 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
146 min = NULL;
147 max = NULL;
148 val = NULL;
149 min_idx = 0;
150 max_idx = 0;
151 val_idx = 0;
152 uint phi_max = phi->req();
153 if( phi_max == 4 ) {
154 for( uint j = 1; j < phi_max; ++j ) {
155 Node *n = phi->in(j);
156 int opcode = n->Opcode();
157 switch( opcode ) {
158 case Op_ConI:
159 {
160 if( min == NULL ) {
161 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
162 min_idx = j;
163 } else {
164 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
165 max_idx = j;
166 if( min->get_int() > max->get_int() ) {
167 // Swap min and max
168 ConNode *temp;
169 uint temp_idx;
170 temp = min; min = max; max = temp;
171 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
172 }
173 }
174 }
175 break;
176 default:
177 {
178 val = n;
179 val_idx = j;
180 }
181 break;
182 }
183 }
184 }
185 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
186 }
187
188
189 //------------------------------check_if_clipping------------------------------
190 // Helper function for RegionNode's identification of FP clipping
191 // Check that inputs to Region come from two IfNodes,
192 //
193 // If
194 // False True
195 // If |
196 // False True |
197 // | | |
198 // RegionNode_inputs
199 //
200 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
201 top_if = NULL;
202 bot_if = NULL;
203
204 // Check control structure above RegionNode for (if ( if ) )
205 Node *in1 = region->in(1);
206 Node *in2 = region->in(2);
207 Node *in3 = region->in(3);
208 // Check that all inputs are projections
209 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
210 Node *in10 = in1->in(0);
211 Node *in20 = in2->in(0);
212 Node *in30 = in3->in(0);
213 // Check that #1 and #2 are ifTrue and ifFalse from same If
214 if( in10 != NULL && in10->is_If() &&
215 in20 != NULL && in20->is_If() &&
216 in30 != NULL && in30->is_If() && in10 == in20 &&
217 (in1->Opcode() != in2->Opcode()) ) {
218 Node *in100 = in10->in(0);
219 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
220 // Check that control for in10 comes from other branch of IF from in3
221 if( in1000 != NULL && in1000->is_If() &&
222 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
223 // Control pattern checks
224 top_if = (IfNode*)in1000;
225 bot_if = (IfNode*)in10;
226 }
227 }
228 }
229
230 return (top_if != NULL);
231 }
232
233
234 //------------------------------check_convf2i_clipping-------------------------
235 // Helper function for RegionNode's identification of FP clipping
236 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
237 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
238 convf2i = NULL;
239
240 // Check for the RShiftNode
241 Node *rshift = phi->in(idx);
242 assert( rshift, "Previous checks ensure phi input is present");
243 if( rshift->Opcode() != Op_RShiftI ) { return false; }
244
245 // Check for the LShiftNode
246 Node *lshift = rshift->in(1);
247 assert( lshift, "Previous checks ensure phi input is present");
248 if( lshift->Opcode() != Op_LShiftI ) { return false; }
249
250 // Check for the ConvF2INode
251 Node *conv = lshift->in(1);
252 if( conv->Opcode() != Op_ConvF2I ) { return false; }
253
254 // Check that shift amounts are only to get sign bits set after F2I
255 jint max_cutoff = max->get_int();
256 jint min_cutoff = min->get_int();
257 jint left_shift = lshift->in(2)->get_int();
258 jint right_shift = rshift->in(2)->get_int();
259 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
260 if( left_shift != right_shift ||
261 0 > left_shift || left_shift >= BitsPerJavaInteger ||
262 max_post_shift < max_cutoff ||
263 max_post_shift < -min_cutoff ) {
264 // Shifts are necessary but current transformation eliminates them
265 return false;
266 }
267
268 // OK to return the result of ConvF2I without shifting
269 convf2i = (ConvF2INode*)conv;
270 return true;
271 }
272
273
274 //------------------------------check_compare_clipping-------------------------
275 // Helper function for RegionNode's identification of FP clipping
276 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
277 Node *i1 = iff->in(1);
278 if ( !i1->is_Bool() ) { return false; }
279 BoolNode *bool1 = i1->as_Bool();
280 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
281 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
282 const Node *cmpF = bool1->in(1);
283 if( cmpF->Opcode() != Op_CmpF ) { return false; }
284 // Test that the float value being compared against
285 // is equivalent to the int value used as a limit
286 Node *nodef = cmpF->in(2);
287 if( nodef->Opcode() != Op_ConF ) { return false; }
288 jfloat conf = nodef->getf();
289 jint coni = limit->get_int();
290 if( ((int)conf) != coni ) { return false; }
291 input = cmpF->in(1);
292 return true;
293 }
294
295 //------------------------------is_unreachable_region--------------------------
296 // Find if the Region node is reachable from the root.
297 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
298 assert(req() == 2, "");
299
300 // First, cut the simple case of fallthrough region when NONE of
301 // region's phis references itself directly or through a data node.
302 uint max = outcnt();
303 uint i;
304 for (i = 0; i < max; i++) {
305 Node* phi = raw_out(i);
306 if (phi != NULL && phi->is_Phi()) {
307 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
308 if (phi->outcnt() == 0)
309 continue; // Safe case - no loops
310 if (phi->outcnt() == 1) {
311 Node* u = phi->raw_out(0);
312 // Skip if only one use is an other Phi or Call or Uncommon trap.
313 // It is safe to consider this case as fallthrough.
314 if (u != NULL && (u->is_Phi() || u->is_CFG()))
315 continue;
316 }
317 // Check when phi references itself directly or through an other node.
318 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
319 break; // Found possible unsafe data loop.
320 }
321 }
322 if (i >= max)
323 return false; // An unsafe case was NOT found - don't need graph walk.
324
325 // Unsafe case - check if the Region node is reachable from root.
326 ResourceMark rm;
327
328 Arena *a = Thread::current()->resource_area();
329 Node_List nstack(a);
330 VectorSet visited(a);
331
332 // Mark all control nodes reachable from root outputs
333 Node *n = (Node*)phase->C->root();
334 nstack.push(n);
335 visited.set(n->_idx);
336 while (nstack.size() != 0) {
337 n = nstack.pop();
338 uint max = n->outcnt();
339 for (uint i = 0; i < max; i++) {
340 Node* m = n->raw_out(i);
341 if (m != NULL && m->is_CFG()) {
342 if (phase->eqv(m, this)) {
343 return false; // We reached the Region node - it is not dead.
344 }
345 if (!visited.test_set(m->_idx))
346 nstack.push(m);
347 }
348 }
349 }
350
351 return true; // The Region node is unreachable - it is dead.
352 }
353
354 //------------------------------Ideal------------------------------------------
355 // Return a node which is more "ideal" than the current node. Must preserve
356 // the CFG, but we can still strip out dead paths.
357 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
358 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
359 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
360
361 // Check for RegionNode with no Phi users and both inputs come from either
362 // arm of the same IF. If found, then the control-flow split is useless.
363 bool has_phis = false;
364 if (can_reshape) { // Need DU info to check for Phi users
365 has_phis = (has_phi() != NULL); // Cache result
366 if (!has_phis) { // No Phi users? Nothing merging?
367 for (uint i = 1; i < req()-1; i++) {
368 Node *if1 = in(i);
369 if( !if1 ) continue;
370 Node *iff = if1->in(0);
371 if( !iff || !iff->is_If() ) continue;
372 for( uint j=i+1; j<req(); j++ ) {
373 if( in(j) && in(j)->in(0) == iff &&
374 if1->Opcode() != in(j)->Opcode() ) {
375 // Add the IF Projections to the worklist. They (and the IF itself)
376 // will be eliminated if dead.
377 phase->is_IterGVN()->add_users_to_worklist(iff);
378 set_req(i, iff->in(0));// Skip around the useless IF diamond
379 set_req(j, NULL);
380 return this; // Record progress
381 }
382 }
383 }
384 }
385 }
386
387 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
388 // degrades to a copy.
389 bool add_to_worklist = false;
390 int cnt = 0; // Count of values merging
391 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
392 int del_it = 0; // The last input path we delete
393 // For all inputs...
394 for( uint i=1; i<req(); ++i ){// For all paths in
395 Node *n = in(i); // Get the input
396 if( n != NULL ) {
397 // Remove useless control copy inputs
398 if( n->is_Region() && n->as_Region()->is_copy() ) {
399 set_req(i, n->nonnull_req());
400 i--;
401 continue;
402 }
403 if( n->is_Proj() ) { // Remove useless rethrows
404 Node *call = n->in(0);
405 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
406 set_req(i, call->in(0));
407 i--;
408 continue;
409 }
410 }
411 if( phase->type(n) == Type::TOP ) {
412 set_req(i, NULL); // Ignore TOP inputs
413 i--;
414 continue;
415 }
416 cnt++; // One more value merging
417
418 } else if (can_reshape) { // Else found dead path with DU info
419 PhaseIterGVN *igvn = phase->is_IterGVN();
420 del_req(i); // Yank path from self
421 del_it = i;
422 uint max = outcnt();
423 DUIterator j;
424 bool progress = true;
425 while(progress) { // Need to establish property over all users
426 progress = false;
427 for (j = outs(); has_out(j); j++) {
428 Node *n = out(j);
429 if( n->req() != req() && n->is_Phi() ) {
430 assert( n->in(0) == this, "" );
431 igvn->hash_delete(n); // Yank from hash before hacking edges
432 n->set_req_X(i,NULL,igvn);// Correct DU info
433 n->del_req(i); // Yank path from Phis
434 if( max != outcnt() ) {
435 progress = true;
436 j = refresh_out_pos(j);
437 max = outcnt();
438 }
439 }
440 }
441 }
442 add_to_worklist = true;
443 i--;
444 }
445 }
446
447 if (can_reshape && cnt == 1) {
448 // Is it dead loop?
449 // If it is LoopNopde it had 2 (+1 itself) inputs and
450 // one of them was cut. The loop is dead if it was EntryContol.
451 assert(!this->is_Loop() || cnt_orig == 3, "Loop node should have 3 inputs");
452 if (this->is_Loop() && del_it == LoopNode::EntryControl ||
453 !this->is_Loop() && has_phis && is_unreachable_region(phase)) {
454 // Yes, the region will be removed during the next step below.
455 // Cut the backedge input and remove phis since no data paths left.
456 // We don't cut outputs to other nodes here since we need to put them
457 // on the worklist.
458 del_req(1);
459 cnt = 0;
460 assert( req() == 1, "no more inputs expected" );
461 uint max = outcnt();
462 bool progress = true;
463 Node *top = phase->C->top();
464 PhaseIterGVN *igvn = phase->is_IterGVN();
465 DUIterator j;
466 while(progress) {
467 progress = false;
468 for (j = outs(); has_out(j); j++) {
469 Node *n = out(j);
470 if( n->is_Phi() ) {
471 assert( igvn->eqv(n->in(0), this), "" );
472 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
473 // Break dead loop data path.
474 // Eagerly replace phis with top to avoid phis copies generation.
475 igvn->add_users_to_worklist(n);
476 igvn->hash_delete(n); // Yank from hash before hacking edges
477 igvn->subsume_node(n, top);
478 if( max != outcnt() ) {
479 progress = true;
480 j = refresh_out_pos(j);
481 max = outcnt();
482 }
483 }
484 }
485 }
486 add_to_worklist = true;
487 }
488 }
489 if (add_to_worklist) {
490 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
491 }
492
493 if( cnt <= 1 ) { // Only 1 path in?
494 set_req(0, NULL); // Null control input for region copy
495 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
496 // No inputs or all inputs are NULL.
497 return NULL;
498 } else if (can_reshape) { // Optimization phase - remove the node
499 PhaseIterGVN *igvn = phase->is_IterGVN();
500 Node *parent_ctrl;
501 if( cnt == 0 ) {
502 assert( req() == 1, "no inputs expected" );
503 // During IGVN phase such region will be subsumed by TOP node
504 // so region's phis will have TOP as control node.
505 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
506 // Also set other user's input to top.
507 parent_ctrl = phase->C->top();
508 } else {
509 // The fallthrough case since we already checked dead loops above.
510 parent_ctrl = in(1);
511 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
512 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
513 }
514 if (!add_to_worklist)
515 igvn->add_users_to_worklist(this); // Check for further allowed opts
516 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
517 Node* n = last_out(i);
518 igvn->hash_delete(n); // Remove from worklist before modifying edges
519 if( n->is_Phi() ) { // Collapse all Phis
520 // Eagerly replace phis to avoid copies generation.
521 igvn->add_users_to_worklist(n);
522 igvn->hash_delete(n); // Yank from hash before hacking edges
523 if( cnt == 0 ) {
524 assert( n->req() == 1, "No data inputs expected" );
525 igvn->subsume_node(n, parent_ctrl); // replaced by top
526 } else {
527 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
528 Node* in1 = n->in(1); // replaced by unique input
529 if( n->as_Phi()->is_unsafe_data_reference(in1) )
530 in1 = phase->C->top(); // replaced by top
531 igvn->subsume_node(n, in1);
532 }
533 }
534 else if( n->is_Region() ) { // Update all incoming edges
535 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
536 uint uses_found = 0;
537 for( uint k=1; k < n->req(); k++ ) {
538 if( n->in(k) == this ) {
539 n->set_req(k, parent_ctrl);
540 uses_found++;
541 }
542 }
543 if( uses_found > 1 ) { // (--i) done at the end of the loop.
544 i -= (uses_found - 1);
545 }
546 }
547 else {
548 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
549 n->set_req(0, parent_ctrl);
550 }
551 #ifdef ASSERT
552 for( uint k=0; k < n->req(); k++ ) {
553 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
554 }
555 #endif
556 }
557 // Remove the RegionNode itself from DefUse info
558 igvn->remove_dead_node(this);
559 return NULL;
560 }
561 return this; // Record progress
562 }
563
564
565 // If a Region flows into a Region, merge into one big happy merge.
566 if (can_reshape) {
567 Node *m = merge_region(this, phase);
568 if (m != NULL) return m;
569 }
570
571 // Check if this region is the root of a clipping idiom on floats
572 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
573 // Check that only one use is a Phi and that it simplifies to two constants +
574 PhiNode* phi = has_unique_phi();
575 if (phi != NULL) { // One Phi user
576 // Check inputs to the Phi
577 ConNode *min;
578 ConNode *max;
579 Node *val;
580 uint min_idx;
581 uint max_idx;
582 uint val_idx;
583 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
584 IfNode *top_if;
585 IfNode *bot_if;
586 if( check_if_clipping( this, bot_if, top_if ) ) {
587 // Control pattern checks, now verify compares
588 Node *top_in = NULL; // value being compared against
589 Node *bot_in = NULL;
590 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
591 check_compare_clipping( false, top_if, max, top_in ) ) {
592 if( bot_in == top_in ) {
593 PhaseIterGVN *gvn = phase->is_IterGVN();
594 assert( gvn != NULL, "Only had DefUse info in IterGVN");
595 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
596
597 // Check for the ConvF2INode
598 ConvF2INode *convf2i;
599 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
600 convf2i->in(1) == bot_in ) {
601 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
602 // max test
603 Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, min ));
604 Node *boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::lt ));
605 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
606 Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
607 Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
608 // min test
609 cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, max ));
610 boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::gt ));
611 iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
612 Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
613 ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
614 // update input edges to region node
615 set_req_X( min_idx, if_min, gvn );
616 set_req_X( max_idx, if_max, gvn );
617 set_req_X( val_idx, ifF, gvn );
618 // remove unnecessary 'LShiftI; RShiftI' idiom
619 gvn->hash_delete(phi);
620 phi->set_req_X( val_idx, convf2i, gvn );
621 gvn->hash_find_insert(phi);
622 // Return transformed region node
623 return this;
624 }
625 }
626 }
627 }
628 }
629 }
630 }
631
632 return NULL;
633 }
634
635
636
637 const RegMask &RegionNode::out_RegMask() const {
638 return RegMask::Empty;
639 }
640
641 // Find the one non-null required input. RegionNode only
642 Node *Node::nonnull_req() const {
643 assert( is_Region(), "" );
644 for( uint i = 1; i < _cnt; i++ )
645 if( in(i) )
646 return in(i);
647 ShouldNotReachHere();
648 return NULL;
649 }
650
651
652 //=============================================================================
653 // note that these functions assume that the _adr_type field is flattened
654 uint PhiNode::hash() const {
655 const Type* at = _adr_type;
656 return TypeNode::hash() + (at ? at->hash() : 0);
657 }
658 uint PhiNode::cmp( const Node &n ) const {
659 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
660 }
661 static inline
662 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
663 if (at == NULL || at == TypePtr::BOTTOM) return at;
664 return Compile::current()->alias_type(at)->adr_type();
665 }
666
667 //----------------------------make---------------------------------------------
668 // create a new phi with edges matching r and set (initially) to x
669 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
670 uint preds = r->req(); // Number of predecessor paths
671 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
672 PhiNode* p = new (Compile::current(), preds) PhiNode(r, t, at);
673 for (uint j = 1; j < preds; j++) {
674 // Fill in all inputs, except those which the region does not yet have
675 if (r->in(j) != NULL)
676 p->init_req(j, x);
677 }
678 return p;
679 }
680 PhiNode* PhiNode::make(Node* r, Node* x) {
681 const Type* t = x->bottom_type();
682 const TypePtr* at = NULL;
683 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
684 return make(r, x, t, at);
685 }
686 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
687 const Type* t = x->bottom_type();
688 const TypePtr* at = NULL;
689 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
690 return new (Compile::current(), r->req()) PhiNode(r, t, at);
691 }
692
693
694 //------------------------slice_memory-----------------------------------------
695 // create a new phi with narrowed memory type
696 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
697 PhiNode* mem = (PhiNode*) clone();
698 *(const TypePtr**)&mem->_adr_type = adr_type;
699 // convert self-loops, or else we get a bad graph
700 for (uint i = 1; i < req(); i++) {
701 if ((const Node*)in(i) == this) mem->set_req(i, mem);
702 }
703 mem->verify_adr_type();
704 return mem;
705 }
706
707 //------------------------split_out_instance-----------------------------------
708 // Split out an instance type from a bottom phi.
709 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
710 const TypeOopPtr *t_oop = at->isa_oopptr();
711 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
712 const TypePtr *t = adr_type();
713 assert(type() == Type::MEMORY &&
714 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
715 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
716 t->is_oopptr()->cast_to_exactness(true)
717 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
718 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
719 "bottom or raw memory required");
720
721 // Check if an appropriate node already exists.
722 Node *region = in(0);
723 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
724 Node* use = region->fast_out(k);
725 if( use->is_Phi()) {
726 PhiNode *phi2 = use->as_Phi();
727 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
728 return phi2;
729 }
730 }
731 }
732 Compile *C = igvn->C;
733 Arena *a = Thread::current()->resource_area();
734 Node_Array node_map = new Node_Array(a);
735 Node_Stack stack(a, C->unique() >> 4);
736 PhiNode *nphi = slice_memory(at);
737 igvn->register_new_node_with_optimizer( nphi );
738 node_map.map(_idx, nphi);
739 stack.push((Node *)this, 1);
740 while(!stack.is_empty()) {
741 PhiNode *ophi = stack.node()->as_Phi();
742 uint i = stack.index();
743 assert(i >= 1, "not control edge");
744 stack.pop();
745 nphi = node_map[ophi->_idx]->as_Phi();
746 for (; i < ophi->req(); i++) {
747 Node *in = ophi->in(i);
748 if (in == NULL || igvn->type(in) == Type::TOP)
749 continue;
750 Node *opt = MemNode::optimize_simple_memory_chain(in, at, igvn);
751 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
752 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
753 opt = node_map[optphi->_idx];
754 if (opt == NULL) {
755 stack.push(ophi, i);
756 nphi = optphi->slice_memory(at);
757 igvn->register_new_node_with_optimizer( nphi );
758 node_map.map(optphi->_idx, nphi);
759 ophi = optphi;
760 i = 0; // will get incremented at top of loop
761 continue;
762 }
763 }
764 nphi->set_req(i, opt);
765 }
766 }
767 return nphi;
768 }
769
770 //------------------------verify_adr_type--------------------------------------
771 #ifdef ASSERT
772 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
773 if (visited.test_set(_idx)) return; //already visited
774
775 // recheck constructor invariants:
776 verify_adr_type(false);
777
778 // recheck local phi/phi consistency:
779 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
780 "adr_type must be consistent across phi nest");
781
782 // walk around
783 for (uint i = 1; i < req(); i++) {
784 Node* n = in(i);
785 if (n == NULL) continue;
786 const Node* np = in(i);
787 if (np->is_Phi()) {
788 np->as_Phi()->verify_adr_type(visited, at);
789 } else if (n->bottom_type() == Type::TOP
790 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
791 // ignore top inputs
792 } else {
793 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
794 // recheck phi/non-phi consistency at leaves:
795 assert((nat != NULL) == (at != NULL), "");
796 assert(nat == at || nat == TypePtr::BOTTOM,
797 "adr_type must be consistent at leaves of phi nest");
798 }
799 }
800 }
801
802 // Verify a whole nest of phis rooted at this one.
803 void PhiNode::verify_adr_type(bool recursive) const {
804 if (is_error_reported()) return; // muzzle asserts when debugging an error
805 if (Node::in_dump()) return; // muzzle asserts when printing
806
807 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
808
809 if (!VerifyAliases) return; // verify thoroughly only if requested
810
811 assert(_adr_type == flatten_phi_adr_type(_adr_type),
812 "Phi::adr_type must be pre-normalized");
813
814 if (recursive) {
815 VectorSet visited(Thread::current()->resource_area());
816 verify_adr_type(visited, _adr_type);
817 }
818 }
819 #endif
820
821
822 //------------------------------Value------------------------------------------
823 // Compute the type of the PhiNode
824 const Type *PhiNode::Value( PhaseTransform *phase ) const {
825 Node *r = in(0); // RegionNode
826 if( !r ) // Copy or dead
827 return in(1) ? phase->type(in(1)) : Type::TOP;
828
829 // Note: During parsing, phis are often transformed before their regions.
830 // This means we have to use type_or_null to defend against untyped regions.
831 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
832 return Type::TOP;
833
834 // Check for trip-counted loop. If so, be smarter.
835 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
836 if( l && l->can_be_counted_loop(phase) &&
837 ((const Node*)l->phi() == this) ) { // Trip counted loop!
838 // protect against init_trip() or limit() returning NULL
839 const Node *init = l->init_trip();
840 const Node *limit = l->limit();
841 if( init != NULL && limit != NULL && l->stride_is_con() ) {
842 const TypeInt *lo = init ->bottom_type()->isa_int();
843 const TypeInt *hi = limit->bottom_type()->isa_int();
844 if( lo && hi ) { // Dying loops might have TOP here
845 int stride = l->stride_con();
846 if( stride < 0 ) { // Down-counter loop
847 const TypeInt *tmp = lo; lo = hi; hi = tmp;
848 stride = -stride;
849 }
850 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
851 return TypeInt::make(lo->_lo,hi->_hi,3);
852 }
853 }
854 }
855
856 // Until we have harmony between classes and interfaces in the type
857 // lattice, we must tread carefully around phis which implicitly
858 // convert the one to the other.
859 const TypePtr* ttp = _type->make_ptr();
860 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
861 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
862 bool is_intf = false;
863 if (ttip != NULL) {
864 ciKlass* k = ttip->klass();
865 if (k->is_loaded() && k->is_interface())
866 is_intf = true;
867 }
868 if (ttkp != NULL) {
869 ciKlass* k = ttkp->klass();
870 if (k->is_loaded() && k->is_interface())
871 is_intf = true;
872 }
873
874 // Default case: merge all inputs
875 const Type *t = Type::TOP; // Merged type starting value
876 for (uint i = 1; i < req(); ++i) {// For all paths in
877 // Reachable control path?
878 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
879 const Type* ti = phase->type(in(i));
880 // We assume that each input of an interface-valued Phi is a true
881 // subtype of that interface. This might not be true of the meet
882 // of all the input types. The lattice is not distributive in
883 // such cases. Ward off asserts in type.cpp by refusing to do
884 // meets between interfaces and proper classes.
885 const TypePtr* tip = ti->make_ptr();
886 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
887 if (tiip) {
888 bool ti_is_intf = false;
889 ciKlass* k = tiip->klass();
890 if (k->is_loaded() && k->is_interface())
891 ti_is_intf = true;
892 if (is_intf != ti_is_intf)
893 { t = _type; break; }
894 }
895 t = t->meet(ti);
896 }
897 }
898
899 // The worst-case type (from ciTypeFlow) should be consistent with "t".
900 // That is, we expect that "t->higher_equal(_type)" holds true.
901 // There are various exceptions:
902 // - Inputs which are phis might in fact be widened unnecessarily.
903 // For example, an input might be a widened int while the phi is a short.
904 // - Inputs might be BotPtrs but this phi is dependent on a null check,
905 // and postCCP has removed the cast which encodes the result of the check.
906 // - The type of this phi is an interface, and the inputs are classes.
907 // - Value calls on inputs might produce fuzzy results.
908 // (Occurrences of this case suggest improvements to Value methods.)
909 //
910 // It is not possible to see Type::BOTTOM values as phi inputs,
911 // because the ciTypeFlow pre-pass produces verifier-quality types.
912 const Type* ft = t->filter(_type); // Worst case type
913
914 #ifdef ASSERT
915 // The following logic has been moved into TypeOopPtr::filter.
916 const Type* jt = t->join(_type);
917 if( jt->empty() ) { // Emptied out???
918
919 // Check for evil case of 't' being a class and '_type' expecting an
920 // interface. This can happen because the bytecodes do not contain
921 // enough type info to distinguish a Java-level interface variable
922 // from a Java-level object variable. If we meet 2 classes which
923 // both implement interface I, but their meet is at 'j/l/O' which
924 // doesn't implement I, we have no way to tell if the result should
925 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
926 // into a Phi which "knows" it's an Interface type we'll have to
927 // uplift the type.
928 if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() )
929 { assert(ft == _type, ""); } // Uplift to interface
930 else if( !t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface() )
931 { assert(ft == _type, ""); } // Uplift to interface
932 // Otherwise it's something stupid like non-overlapping int ranges
933 // found on dying counted loops.
934 else
935 { assert(ft == Type::TOP, ""); } // Canonical empty value
936 }
937
938 else {
939
940 // If we have an interface-typed Phi and we narrow to a class type, the join
941 // should report back the class. However, if we have a J/L/Object
942 // class-typed Phi and an interface flows in, it's possible that the meet &
943 // join report an interface back out. This isn't possible but happens
944 // because the type system doesn't interact well with interfaces.
945 const TypePtr *jtp = jt->make_ptr();
946 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
947 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
948 if( jtip && ttip ) {
949 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
950 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
951 // Happens in a CTW of rt.jar, 320-341, no extra flags
952 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
953 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
954 jt = ft;
955 }
956 }
957 if( jtkp && ttkp ) {
958 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
959 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
960 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
961 ft->isa_narrowoop() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
962 jt = ft;
963 }
964 }
965 if (jt != ft && jt->base() == ft->base()) {
966 if (jt->isa_int() &&
967 jt->is_int()->_lo == ft->is_int()->_lo &&
968 jt->is_int()->_hi == ft->is_int()->_hi)
969 jt = ft;
970 if (jt->isa_long() &&
971 jt->is_long()->_lo == ft->is_long()->_lo &&
972 jt->is_long()->_hi == ft->is_long()->_hi)
973 jt = ft;
974 }
975 if (jt != ft) {
976 tty->print("merge type: "); t->dump(); tty->cr();
977 tty->print("kill type: "); _type->dump(); tty->cr();
978 tty->print("join type: "); jt->dump(); tty->cr();
979 tty->print("filter type: "); ft->dump(); tty->cr();
980 }
981 assert(jt == ft, "");
982 }
983 #endif //ASSERT
984
985 // Deal with conversion problems found in data loops.
986 ft = phase->saturate(ft, phase->type_or_null(this), _type);
987
988 return ft;
989 }
990
991
992 //------------------------------is_diamond_phi---------------------------------
993 // Does this Phi represent a simple well-shaped diamond merge? Return the
994 // index of the true path or 0 otherwise.
995 int PhiNode::is_diamond_phi() const {
996 // Check for a 2-path merge
997 Node *region = in(0);
998 if( !region ) return 0;
999 if( region->req() != 3 ) return 0;
1000 if( req() != 3 ) return 0;
1001 // Check that both paths come from the same If
1002 Node *ifp1 = region->in(1);
1003 Node *ifp2 = region->in(2);
1004 if( !ifp1 || !ifp2 ) return 0;
1005 Node *iff = ifp1->in(0);
1006 if( !iff || !iff->is_If() ) return 0;
1007 if( iff != ifp2->in(0) ) return 0;
1008 // Check for a proper bool/cmp
1009 const Node *b = iff->in(1);
1010 if( !b->is_Bool() ) return 0;
1011 const Node *cmp = b->in(1);
1012 if( !cmp->is_Cmp() ) return 0;
1013
1014 // Check for branching opposite expected
1015 if( ifp2->Opcode() == Op_IfTrue ) {
1016 assert( ifp1->Opcode() == Op_IfFalse, "" );
1017 return 2;
1018 } else {
1019 assert( ifp1->Opcode() == Op_IfTrue, "" );
1020 return 1;
1021 }
1022 }
1023
1024 //----------------------------check_cmove_id-----------------------------------
1025 // Check for CMove'ing a constant after comparing against the constant.
1026 // Happens all the time now, since if we compare equality vs a constant in
1027 // the parser, we "know" the variable is constant on one path and we force
1028 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1029 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1030 // general in that we don't need constants. Since CMove's are only inserted
1031 // in very special circumstances, we do it here on generic Phi's.
1032 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1033 assert(true_path !=0, "only diamond shape graph expected");
1034
1035 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1036 // phi->region->if_proj->ifnode->bool->cmp
1037 Node* region = in(0);
1038 Node* iff = region->in(1)->in(0);
1039 BoolNode* b = iff->in(1)->as_Bool();
1040 Node* cmp = b->in(1);
1041 Node* tval = in(true_path);
1042 Node* fval = in(3-true_path);
1043 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1044 if (id == NULL)
1045 return NULL;
1046
1047 // Either value might be a cast that depends on a branch of 'iff'.
1048 // Since the 'id' value will float free of the diamond, either
1049 // decast or return failure.
1050 Node* ctl = id->in(0);
1051 if (ctl != NULL && ctl->in(0) == iff) {
1052 if (id->is_ConstraintCast()) {
1053 return id->in(1);
1054 } else {
1055 // Don't know how to disentangle this value.
1056 return NULL;
1057 }
1058 }
1059
1060 return id;
1061 }
1062
1063 //------------------------------Identity---------------------------------------
1064 // Check for Region being Identity.
1065 Node *PhiNode::Identity( PhaseTransform *phase ) {
1066 // Check for no merging going on
1067 // (There used to be special-case code here when this->region->is_Loop.
1068 // It would check for a tributary phi on the backedge that the main phi
1069 // trivially, perhaps with a single cast. The unique_input method
1070 // does all this and more, by reducing such tributaries to 'this'.)
1071 Node* uin = unique_input(phase);
1072 if (uin != NULL) {
1073 return uin;
1074 }
1075
1076 int true_path = is_diamond_phi();
1077 if (true_path != 0) {
1078 Node* id = is_cmove_id(phase, true_path);
1079 if (id != NULL) return id;
1080 }
1081
1082 return this; // No identity
1083 }
1084
1085 //-----------------------------unique_input------------------------------------
1086 // Find the unique value, discounting top, self-loops, and casts.
1087 // Return top if there are no inputs, and self if there are multiple.
1088 Node* PhiNode::unique_input(PhaseTransform* phase) {
1089 // 1) One unique direct input, or
1090 // 2) some of the inputs have an intervening ConstraintCast and
1091 // the type of input is the same or sharper (more specific)
1092 // than the phi's type.
1093 // 3) an input is a self loop
1094 //
1095 // 1) input or 2) input or 3) input __
1096 // / \ / \ \ / \
1097 // \ / | cast phi cast
1098 // phi \ / / \ /
1099 // phi / --
1100
1101 Node* r = in(0); // RegionNode
1102 if (r == NULL) return in(1); // Already degraded to a Copy
1103 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
1104 Node* direct_input = NULL; // The unique direct input
1105
1106 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1107 Node* rc = r->in(i);
1108 if (rc == NULL || phase->type(rc) == Type::TOP)
1109 continue; // ignore unreachable control path
1110 Node* n = in(i);
1111 if (n == NULL)
1112 continue;
1113 Node* un = n->uncast();
1114 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1115 continue; // ignore if top, or in(i) and "this" are in a data cycle
1116 }
1117 // Check for a unique uncasted input
1118 if (uncasted_input == NULL) {
1119 uncasted_input = un;
1120 } else if (uncasted_input != un) {
1121 uncasted_input = NodeSentinel; // no unique uncasted input
1122 }
1123 // Check for a unique direct input
1124 if (direct_input == NULL) {
1125 direct_input = n;
1126 } else if (direct_input != n) {
1127 direct_input = NodeSentinel; // no unique direct input
1128 }
1129 }
1130 if (direct_input == NULL) {
1131 return phase->C->top(); // no inputs
1132 }
1133 assert(uncasted_input != NULL,"");
1134
1135 if (direct_input != NodeSentinel) {
1136 return direct_input; // one unique direct input
1137 }
1138 if (uncasted_input != NodeSentinel &&
1139 phase->type(uncasted_input)->higher_equal(type())) {
1140 return uncasted_input; // one unique uncasted input
1141 }
1142
1143 // Nothing.
1144 return NULL;
1145 }
1146
1147 //------------------------------is_x2logic-------------------------------------
1148 // Check for simple convert-to-boolean pattern
1149 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1150 // Convert Phi to an ConvIB.
1151 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1152 assert(true_path !=0, "only diamond shape graph expected");
1153 // Convert the true/false index into an expected 0/1 return.
1154 // Map 2->0 and 1->1.
1155 int flipped = 2-true_path;
1156
1157 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1158 // phi->region->if_proj->ifnode->bool->cmp
1159 Node *region = phi->in(0);
1160 Node *iff = region->in(1)->in(0);
1161 BoolNode *b = (BoolNode*)iff->in(1);
1162 const CmpNode *cmp = (CmpNode*)b->in(1);
1163
1164 Node *zero = phi->in(1);
1165 Node *one = phi->in(2);
1166 const Type *tzero = phase->type( zero );
1167 const Type *tone = phase->type( one );
1168
1169 // Check for compare vs 0
1170 const Type *tcmp = phase->type(cmp->in(2));
1171 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1172 // Allow cmp-vs-1 if the other input is bounded by 0-1
1173 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1174 return NULL;
1175 flipped = 1-flipped; // Test is vs 1 instead of 0!
1176 }
1177
1178 // Check for setting zero/one opposite expected
1179 if( tzero == TypeInt::ZERO ) {
1180 if( tone == TypeInt::ONE ) {
1181 } else return NULL;
1182 } else if( tzero == TypeInt::ONE ) {
1183 if( tone == TypeInt::ZERO ) {
1184 flipped = 1-flipped;
1185 } else return NULL;
1186 } else return NULL;
1187
1188 // Check for boolean test backwards
1189 if( b->_test._test == BoolTest::ne ) {
1190 } else if( b->_test._test == BoolTest::eq ) {
1191 flipped = 1-flipped;
1192 } else return NULL;
1193
1194 // Build int->bool conversion
1195 Node *n = new (phase->C, 2) Conv2BNode( cmp->in(1) );
1196 if( flipped )
1197 n = new (phase->C, 3) XorINode( phase->transform(n), phase->intcon(1) );
1198
1199 return n;
1200 }
1201
1202 //------------------------------is_cond_add------------------------------------
1203 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1204 // To be profitable the control flow has to disappear; there can be no other
1205 // values merging here. We replace the test-and-branch with:
1206 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1207 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1208 // Then convert Y to 0-or-Y and finally add.
1209 // This is a key transform for SpecJava _201_compress.
1210 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1211 assert(true_path !=0, "only diamond shape graph expected");
1212
1213 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1214 // phi->region->if_proj->ifnode->bool->cmp
1215 RegionNode *region = (RegionNode*)phi->in(0);
1216 Node *iff = region->in(1)->in(0);
1217 BoolNode* b = iff->in(1)->as_Bool();
1218 const CmpNode *cmp = (CmpNode*)b->in(1);
1219
1220 // Make sure only merging this one phi here
1221 if (region->has_unique_phi() != phi) return NULL;
1222
1223 // Make sure each arm of the diamond has exactly one output, which we assume
1224 // is the region. Otherwise, the control flow won't disappear.
1225 if (region->in(1)->outcnt() != 1) return NULL;
1226 if (region->in(2)->outcnt() != 1) return NULL;
1227
1228 // Check for "(P < Q)" of type signed int
1229 if (b->_test._test != BoolTest::lt) return NULL;
1230 if (cmp->Opcode() != Op_CmpI) return NULL;
1231
1232 Node *p = cmp->in(1);
1233 Node *q = cmp->in(2);
1234 Node *n1 = phi->in( true_path);
1235 Node *n2 = phi->in(3-true_path);
1236
1237 int op = n1->Opcode();
1238 if( op != Op_AddI // Need zero as additive identity
1239 /*&&op != Op_SubI &&
1240 op != Op_AddP &&
1241 op != Op_XorI &&
1242 op != Op_OrI*/ )
1243 return NULL;
1244
1245 Node *x = n2;
1246 Node *y = n1->in(1);
1247 if( n2 == n1->in(1) ) {
1248 y = n1->in(2);
1249 } else if( n2 == n1->in(1) ) {
1250 } else return NULL;
1251
1252 // Not so profitable if compare and add are constants
1253 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1254 return NULL;
1255
1256 Node *cmplt = phase->transform( new (phase->C, 3) CmpLTMaskNode(p,q) );
1257 Node *j_and = phase->transform( new (phase->C, 3) AndINode(cmplt,y) );
1258 return new (phase->C, 3) AddINode(j_and,x);
1259 }
1260
1261 //------------------------------is_absolute------------------------------------
1262 // Check for absolute value.
1263 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1264 assert(true_path !=0, "only diamond shape graph expected");
1265
1266 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1267 int phi_x_idx = 0; // Index of phi input where to find naked x
1268
1269 // ABS ends with the merge of 2 control flow paths.
1270 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1271 int false_path = 3 - true_path;
1272
1273 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1274 // phi->region->if_proj->ifnode->bool->cmp
1275 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1276
1277 // Check bool sense
1278 switch( bol->_test._test ) {
1279 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1280 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1281 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1282 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1283 default: return NULL; break;
1284 }
1285
1286 // Test is next
1287 Node *cmp = bol->in(1);
1288 const Type *tzero = NULL;
1289 switch( cmp->Opcode() ) {
1290 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1291 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1292 default: return NULL;
1293 }
1294
1295 // Find zero input of compare; the other input is being abs'd
1296 Node *x = NULL;
1297 bool flip = false;
1298 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1299 x = cmp->in(3 - cmp_zero_idx);
1300 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1301 // The test is inverted, we should invert the result...
1302 x = cmp->in(cmp_zero_idx);
1303 flip = true;
1304 } else {
1305 return NULL;
1306 }
1307
1308 // Next get the 2 pieces being selected, one is the original value
1309 // and the other is the negated value.
1310 if( phi_root->in(phi_x_idx) != x ) return NULL;
1311
1312 // Check other phi input for subtract node
1313 Node *sub = phi_root->in(3 - phi_x_idx);
1314
1315 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1316 if( tzero == TypeF::ZERO ) {
1317 if( sub->Opcode() != Op_SubF ||
1318 sub->in(2) != x ||
1319 phase->type(sub->in(1)) != tzero ) return NULL;
1320 x = new (phase->C, 2) AbsFNode(x);
1321 if (flip) {
1322 x = new (phase->C, 3) SubFNode(sub->in(1), phase->transform(x));
1323 }
1324 } else {
1325 if( sub->Opcode() != Op_SubD ||
1326 sub->in(2) != x ||
1327 phase->type(sub->in(1)) != tzero ) return NULL;
1328 x = new (phase->C, 2) AbsDNode(x);
1329 if (flip) {
1330 x = new (phase->C, 3) SubDNode(sub->in(1), phase->transform(x));
1331 }
1332 }
1333
1334 return x;
1335 }
1336
1337 //------------------------------split_once-------------------------------------
1338 // Helper for split_flow_path
1339 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1340 igvn->hash_delete(n); // Remove from hash before hacking edges
1341
1342 uint j = 1;
1343 for( uint i = phi->req()-1; i > 0; i-- ) {
1344 if( phi->in(i) == val ) { // Found a path with val?
1345 // Add to NEW Region/Phi, no DU info
1346 newn->set_req( j++, n->in(i) );
1347 // Remove from OLD Region/Phi
1348 n->del_req(i);
1349 }
1350 }
1351
1352 // Register the new node but do not transform it. Cannot transform until the
1353 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1354 igvn->register_new_node_with_optimizer( newn );
1355 // Now I can point to the new node.
1356 n->add_req(newn);
1357 igvn->_worklist.push(n);
1358 }
1359
1360 //------------------------------split_flow_path--------------------------------
1361 // Check for merging identical values and split flow paths
1362 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1363 BasicType bt = phi->type()->basic_type();
1364 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1365 return NULL; // Bail out on funny non-value stuff
1366 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1367 return NULL; // third unequal input to be worth doing
1368
1369 // Scan for a constant
1370 uint i;
1371 for( i = 1; i < phi->req()-1; i++ ) {
1372 Node *n = phi->in(i);
1373 if( !n ) return NULL;
1374 if( phase->type(n) == Type::TOP ) return NULL;
1375 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN )
1376 break;
1377 }
1378 if( i >= phi->req() ) // Only split for constants
1379 return NULL;
1380
1381 Node *val = phi->in(i); // Constant to split for
1382 uint hit = 0; // Number of times it occurs
1383
1384 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1385 Node *n = phi->in(i);
1386 if( !n ) return NULL;
1387 if( phase->type(n) == Type::TOP ) return NULL;
1388 if( phi->in(i) == val )
1389 hit++;
1390 }
1391
1392 if( hit <= 1 || // Make sure we find 2 or more
1393 hit == phi->req()-1 ) // and not ALL the same value
1394 return NULL;
1395
1396 // Now start splitting out the flow paths that merge the same value.
1397 // Split first the RegionNode.
1398 PhaseIterGVN *igvn = phase->is_IterGVN();
1399 Node *r = phi->region();
1400 RegionNode *newr = new (phase->C, hit+1) RegionNode(hit+1);
1401 split_once(igvn, phi, val, r, newr);
1402
1403 // Now split all other Phis than this one
1404 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1405 Node* phi2 = r->fast_out(k);
1406 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1407 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1408 split_once(igvn, phi, val, phi2, newphi);
1409 }
1410 }
1411
1412 // Clean up this guy
1413 igvn->hash_delete(phi);
1414 for( i = phi->req()-1; i > 0; i-- ) {
1415 if( phi->in(i) == val ) {
1416 phi->del_req(i);
1417 }
1418 }
1419 phi->add_req(val);
1420
1421 return phi;
1422 }
1423
1424 //=============================================================================
1425 //------------------------------simple_data_loop_check-------------------------
1426 // Try to determining if the phi node in a simple safe/unsafe data loop.
1427 // Returns:
1428 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1429 // Safe - safe case when the phi and it's inputs reference only safe data
1430 // nodes;
1431 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1432 // is no reference back to the phi - need a graph walk
1433 // to determine if it is in a loop;
1434 // UnsafeLoop - unsafe case when the phi references itself directly or through
1435 // unsafe data node.
1436 // Note: a safe data node is a node which could/never reference itself during
1437 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1438 // I mark Phi nodes as safe node not only because they can reference itself
1439 // but also to prevent mistaking the fallthrough case inside an outer loop
1440 // as dead loop when the phi references itselfs through an other phi.
1441 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1442 // It is unsafe loop if the phi node references itself directly.
1443 if (in == (Node*)this)
1444 return UnsafeLoop; // Unsafe loop
1445 // Unsafe loop if the phi node references itself through an unsafe data node.
1446 // Exclude cases with null inputs or data nodes which could reference
1447 // itself (safe for dead loops).
1448 if (in != NULL && !in->is_dead_loop_safe()) {
1449 // Check inputs of phi's inputs also.
1450 // It is much less expensive then full graph walk.
1451 uint cnt = in->req();
1452 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1453 for (; i < cnt; ++i) {
1454 Node* m = in->in(i);
1455 if (m == (Node*)this)
1456 return UnsafeLoop; // Unsafe loop
1457 if (m != NULL && !m->is_dead_loop_safe()) {
1458 // Check the most common case (about 30% of all cases):
1459 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1460 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1461 if (m1 == (Node*)this)
1462 return UnsafeLoop; // Unsafe loop
1463 if (m1 != NULL && m1 == m->in(2) &&
1464 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1465 continue; // Safe case
1466 }
1467 // The phi references an unsafe node - need full analysis.
1468 return Unsafe;
1469 }
1470 }
1471 }
1472 return Safe; // Safe case - we can optimize the phi node.
1473 }
1474
1475 //------------------------------is_unsafe_data_reference-----------------------
1476 // If phi can be reached through the data input - it is data loop.
1477 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1478 assert(req() > 1, "");
1479 // First, check simple cases when phi references itself directly or
1480 // through an other node.
1481 LoopSafety safety = simple_data_loop_check(in);
1482 if (safety == UnsafeLoop)
1483 return true; // phi references itself - unsafe loop
1484 else if (safety == Safe)
1485 return false; // Safe case - phi could be replaced with the unique input.
1486
1487 // Unsafe case when we should go through data graph to determine
1488 // if the phi references itself.
1489
1490 ResourceMark rm;
1491
1492 Arena *a = Thread::current()->resource_area();
1493 Node_List nstack(a);
1494 VectorSet visited(a);
1495
1496 nstack.push(in); // Start with unique input.
1497 visited.set(in->_idx);
1498 while (nstack.size() != 0) {
1499 Node* n = nstack.pop();
1500 uint cnt = n->req();
1501 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1502 for (; i < cnt; i++) {
1503 Node* m = n->in(i);
1504 if (m == (Node*)this) {
1505 return true; // Data loop
1506 }
1507 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1508 if (!visited.test_set(m->_idx))
1509 nstack.push(m);
1510 }
1511 }
1512 }
1513 return false; // The phi is not reachable from its inputs
1514 }
1515
1516
1517 //------------------------------Ideal------------------------------------------
1518 // Return a node which is more "ideal" than the current node. Must preserve
1519 // the CFG, but we can still strip out dead paths.
1520 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1521 // The next should never happen after 6297035 fix.
1522 if( is_copy() ) // Already degraded to a Copy ?
1523 return NULL; // No change
1524
1525 Node *r = in(0); // RegionNode
1526 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1527
1528 // Note: During parsing, phis are often transformed before their regions.
1529 // This means we have to use type_or_null to defend against untyped regions.
1530 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1531 return NULL; // No change
1532
1533 Node *top = phase->C->top();
1534
1535 // The are 2 situations when only one valid phi's input is left
1536 // (in addition to Region input).
1537 // One: region is not loop - replace phi with this input.
1538 // Two: region is loop - replace phi with top since this data path is dead
1539 // and we need to break the dead data loop.
1540 Node* progress = NULL; // Record if any progress made
1541 for( uint j = 1; j < req(); ++j ){ // For all paths in
1542 // Check unreachable control paths
1543 Node* rc = r->in(j);
1544 Node* n = in(j); // Get the input
1545 if (rc == NULL || phase->type(rc) == Type::TOP) {
1546 if (n != top) { // Not already top?
1547 set_req(j, top); // Nuke it down
1548 progress = this; // Record progress
1549 }
1550 }
1551 }
1552
1553 Node* uin = unique_input(phase);
1554 if (uin == top) { // Simplest case: no alive inputs.
1555 if (can_reshape) // IGVN transformation
1556 return top;
1557 else
1558 return NULL; // Identity will return TOP
1559 } else if (uin != NULL) {
1560 // Only one not-NULL unique input path is left.
1561 // Determine if this input is backedge of a loop.
1562 // (Skip new phis which have no uses and dead regions).
1563 if( outcnt() > 0 && r->in(0) != NULL ) {
1564 // First, take the short cut when we know it is a loop and
1565 // the EntryControl data path is dead.
1566 assert(!r->is_Loop() || r->req() == 3, "Loop node should have 3 inputs");
1567 // Then, check if there is a data loop when phi references itself directly
1568 // or through other data nodes.
1569 if( r->is_Loop() && !phase->eqv_uncast(uin, in(LoopNode::EntryControl)) ||
1570 !r->is_Loop() && is_unsafe_data_reference(uin) ) {
1571 // Break this data loop to avoid creation of a dead loop.
1572 if (can_reshape) {
1573 return top;
1574 } else {
1575 // We can't return top if we are in Parse phase - cut inputs only
1576 // let Identity to handle the case.
1577 replace_edge(uin, top);
1578 return NULL;
1579 }
1580 }
1581 }
1582
1583 // One unique input.
1584 debug_only(Node* ident = Identity(phase));
1585 // The unique input must eventually be detected by the Identity call.
1586 #ifdef ASSERT
1587 if (ident != uin && !ident->is_top()) {
1588 // print this output before failing assert
1589 r->dump(3);
1590 this->dump(3);
1591 ident->dump();
1592 uin->dump();
1593 }
1594 #endif
1595 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1596 return NULL;
1597 }
1598
1599
1600 Node* opt = NULL;
1601 int true_path = is_diamond_phi();
1602 if( true_path != 0 ) {
1603 // Check for CMove'ing identity. If it would be unsafe,
1604 // handle it here. In the safe case, let Identity handle it.
1605 Node* unsafe_id = is_cmove_id(phase, true_path);
1606 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1607 opt = unsafe_id;
1608
1609 // Check for simple convert-to-boolean pattern
1610 if( opt == NULL )
1611 opt = is_x2logic(phase, this, true_path);
1612
1613 // Check for absolute value
1614 if( opt == NULL )
1615 opt = is_absolute(phase, this, true_path);
1616
1617 // Check for conditional add
1618 if( opt == NULL && can_reshape )
1619 opt = is_cond_add(phase, this, true_path);
1620
1621 // These 4 optimizations could subsume the phi:
1622 // have to check for a dead data loop creation.
1623 if( opt != NULL ) {
1624 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1625 // Found dead loop.
1626 if( can_reshape )
1627 return top;
1628 // We can't return top if we are in Parse phase - cut inputs only
1629 // to stop further optimizations for this phi. Identity will return TOP.
1630 assert(req() == 3, "only diamond merge phi here");
1631 set_req(1, top);
1632 set_req(2, top);
1633 return NULL;
1634 } else {
1635 return opt;
1636 }
1637 }
1638 }
1639
1640 // Check for merging identical values and split flow paths
1641 if (can_reshape) {
1642 opt = split_flow_path(phase, this);
1643 // This optimization only modifies phi - don't need to check for dead loop.
1644 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1645 if (opt != NULL) return opt;
1646 }
1647
1648 // Split phis through memory merges, so that the memory merges will go away.
1649 // Piggy-back this transformation on the search for a unique input....
1650 // It will be as if the merged memory is the unique value of the phi.
1651 // (Do not attempt this optimization unless parsing is complete.
1652 // It would make the parser's memory-merge logic sick.)
1653 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1654 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1655 // see if this phi should be sliced
1656 uint merge_width = 0;
1657 bool saw_self = false;
1658 for( uint i=1; i<req(); ++i ) {// For all paths in
1659 Node *ii = in(i);
1660 if (ii->is_MergeMem()) {
1661 MergeMemNode* n = ii->as_MergeMem();
1662 merge_width = MAX2(merge_width, n->req());
1663 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1664 }
1665 }
1666
1667 // This restriction is temporarily necessary to ensure termination:
1668 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1669
1670 if (merge_width > Compile::AliasIdxRaw) {
1671 // found at least one non-empty MergeMem
1672 const TypePtr* at = adr_type();
1673 if (at != TypePtr::BOTTOM) {
1674 // Patch the existing phi to select an input from the merge:
1675 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1676 // Phi:AT1(...m1...)
1677 int alias_idx = phase->C->get_alias_index(at);
1678 for (uint i=1; i<req(); ++i) {
1679 Node *ii = in(i);
1680 if (ii->is_MergeMem()) {
1681 MergeMemNode* n = ii->as_MergeMem();
1682 // compress paths and change unreachable cycles to TOP
1683 // If not, we can update the input infinitely along a MergeMem cycle
1684 // Equivalent code is in MemNode::Ideal_common
1685 Node *m = phase->transform(n);
1686 if (outcnt() == 0) { // Above transform() may kill us!
1687 progress = phase->C->top();
1688 break;
1689 }
1690 // If transformed to a MergeMem, get the desired slice
1691 // Otherwise the returned node represents memory for every slice
1692 Node *new_mem = (m->is_MergeMem()) ?
1693 m->as_MergeMem()->memory_at(alias_idx) : m;
1694 // Update input if it is progress over what we have now
1695 if (new_mem != ii) {
1696 set_req(i, new_mem);
1697 progress = this;
1698 }
1699 }
1700 }
1701 } else {
1702 // We know that at least one MergeMem->base_memory() == this
1703 // (saw_self == true). If all other inputs also references this phi
1704 // (directly or through data nodes) - it is dead loop.
1705 bool saw_safe_input = false;
1706 for (uint j = 1; j < req(); ++j) {
1707 Node *n = in(j);
1708 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1709 continue; // skip known cases
1710 if (!is_unsafe_data_reference(n)) {
1711 saw_safe_input = true; // found safe input
1712 break;
1713 }
1714 }
1715 if (!saw_safe_input)
1716 return top; // all inputs reference back to this phi - dead loop
1717
1718 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1719 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1720 PhaseIterGVN *igvn = phase->is_IterGVN();
1721 Node* hook = new (phase->C, 1) Node(1);
1722 PhiNode* new_base = (PhiNode*) clone();
1723 // Must eagerly register phis, since they participate in loops.
1724 if (igvn) {
1725 igvn->register_new_node_with_optimizer(new_base);
1726 hook->add_req(new_base);
1727 }
1728 MergeMemNode* result = MergeMemNode::make(phase->C, new_base);
1729 for (uint i = 1; i < req(); ++i) {
1730 Node *ii = in(i);
1731 if (ii->is_MergeMem()) {
1732 MergeMemNode* n = ii->as_MergeMem();
1733 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1734 // If we have not seen this slice yet, make a phi for it.
1735 bool made_new_phi = false;
1736 if (mms.is_empty()) {
1737 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1738 made_new_phi = true;
1739 if (igvn) {
1740 igvn->register_new_node_with_optimizer(new_phi);
1741 hook->add_req(new_phi);
1742 }
1743 mms.set_memory(new_phi);
1744 }
1745 Node* phi = mms.memory();
1746 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1747 phi->set_req(i, mms.memory2());
1748 }
1749 }
1750 }
1751 // Distribute all self-loops.
1752 { // (Extra braces to hide mms.)
1753 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1754 Node* phi = mms.memory();
1755 for (uint i = 1; i < req(); ++i) {
1756 if (phi->in(i) == this) phi->set_req(i, phi);
1757 }
1758 }
1759 }
1760 // now transform the new nodes, and return the mergemem
1761 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1762 Node* phi = mms.memory();
1763 mms.set_memory(phase->transform(phi));
1764 }
1765 if (igvn) { // Unhook.
1766 igvn->hash_delete(hook);
1767 for (uint i = 1; i < hook->req(); i++) {
1768 hook->set_req(i, NULL);
1769 }
1770 }
1771 // Replace self with the result.
1772 return result;
1773 }
1774 }
1775 //
1776 // Other optimizations on the memory chain
1777 //
1778 const TypePtr* at = adr_type();
1779 for( uint i=1; i<req(); ++i ) {// For all paths in
1780 Node *ii = in(i);
1781 Node *new_in = MemNode::optimize_memory_chain(ii, at, phase);
1782 if (ii != new_in ) {
1783 set_req(i, new_in);
1784 progress = this;
1785 }
1786 }
1787 }
1788
1789 #ifdef _LP64
1790 // Push DecodeN down through phi.
1791 // The rest of phi graph will transform by split EncodeP node though phis up.
1792 if (UseCompressedOops && can_reshape && progress == NULL) {
1793 bool may_push = true;
1794 bool has_decodeN = false;
1795 Node* in_decodeN = NULL;
1796 for (uint i=1; i<req(); ++i) {// For all paths in
1797 Node *ii = in(i);
1798 if (ii->is_DecodeN() && ii->bottom_type() == bottom_type()) {
1799 // Note: in_decodeN is used only to define the type of new phi.
1800 // Find a non dead path otherwise phi type will be wrong.
1801 if (ii->in(1)->bottom_type() != Type::TOP) {
1802 has_decodeN = true;
1803 in_decodeN = ii->in(1);
1804 }
1805 } else if (!ii->is_Phi()) {
1806 may_push = false;
1807 }
1808 }
1809
1810 if (has_decodeN && may_push) {
1811 PhaseIterGVN *igvn = phase->is_IterGVN();
1812 PhiNode *new_phi = PhiNode::make_blank(in(0), in_decodeN);
1813 uint orig_cnt = req();
1814 for (uint i=1; i<req(); ++i) {// For all paths in
1815 Node *ii = in(i);
1816 Node* new_ii = NULL;
1817 if (ii->is_DecodeN()) {
1818 assert(ii->bottom_type() == bottom_type(), "sanity");
1819 new_ii = ii->in(1);
1820 } else {
1821 assert(ii->is_Phi(), "sanity");
1822 if (ii->as_Phi() == this) {
1823 new_ii = new_phi;
1824 } else {
1825 new_ii = new (phase->C, 2) EncodePNode(ii, in_decodeN->bottom_type());
1826 igvn->register_new_node_with_optimizer(new_ii);
1827 }
1828 }
1829 new_phi->set_req(i, new_ii);
1830 }
1831 igvn->register_new_node_with_optimizer(new_phi, this);
1832 progress = new (phase->C, 2) DecodeNNode(new_phi, bottom_type());
1833 }
1834 }
1835 #endif
1836
1837 return progress; // Return any progress
1838 }
1839
1840 //------------------------------is_tripcount-----------------------------------
1841 bool PhiNode::is_tripcount() const {
1842 return (in(0) != NULL && in(0)->is_CountedLoop() &&
1843 in(0)->as_CountedLoop()->phi() == this);
1844 }
1845
1846 //------------------------------out_RegMask------------------------------------
1847 const RegMask &PhiNode::in_RegMask(uint i) const {
1848 return i ? out_RegMask() : RegMask::Empty;
1849 }
1850
1851 const RegMask &PhiNode::out_RegMask() const {
1852 uint ideal_reg = Matcher::base2reg[_type->base()];
1853 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
1854 if( ideal_reg == 0 ) return RegMask::Empty;
1855 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
1856 }
1857
1858 #ifndef PRODUCT
1859 void PhiNode::dump_spec(outputStream *st) const {
1860 TypeNode::dump_spec(st);
1861 if (is_tripcount()) {
1862 st->print(" #tripcount");
1863 }
1864 }
1865 #endif
1866
1867
1868 //=============================================================================
1869 const Type *GotoNode::Value( PhaseTransform *phase ) const {
1870 // If the input is reachable, then we are executed.
1871 // If the input is not reachable, then we are not executed.
1872 return phase->type(in(0));
1873 }
1874
1875 Node *GotoNode::Identity( PhaseTransform *phase ) {
1876 return in(0); // Simple copy of incoming control
1877 }
1878
1879 const RegMask &GotoNode::out_RegMask() const {
1880 return RegMask::Empty;
1881 }
1882
1883 //=============================================================================
1884 const RegMask &JumpNode::out_RegMask() const {
1885 return RegMask::Empty;
1886 }
1887
1888 //=============================================================================
1889 const RegMask &JProjNode::out_RegMask() const {
1890 return RegMask::Empty;
1891 }
1892
1893 //=============================================================================
1894 const RegMask &CProjNode::out_RegMask() const {
1895 return RegMask::Empty;
1896 }
1897
1898
1899
1900 //=============================================================================
1901
1902 uint PCTableNode::hash() const { return Node::hash() + _size; }
1903 uint PCTableNode::cmp( const Node &n ) const
1904 { return _size == ((PCTableNode&)n)._size; }
1905
1906 const Type *PCTableNode::bottom_type() const {
1907 const Type** f = TypeTuple::fields(_size);
1908 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
1909 return TypeTuple::make(_size, f);
1910 }
1911
1912 //------------------------------Value------------------------------------------
1913 // Compute the type of the PCTableNode. If reachable it is a tuple of
1914 // Control, otherwise the table targets are not reachable
1915 const Type *PCTableNode::Value( PhaseTransform *phase ) const {
1916 if( phase->type(in(0)) == Type::CONTROL )
1917 return bottom_type();
1918 return Type::TOP; // All paths dead? Then so are we
1919 }
1920
1921 //------------------------------Ideal------------------------------------------
1922 // Return a node which is more "ideal" than the current node. Strip out
1923 // control copies
1924 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1925 return remove_dead_region(phase, can_reshape) ? this : NULL;
1926 }
1927
1928 //=============================================================================
1929 uint JumpProjNode::hash() const {
1930 return Node::hash() + _dest_bci;
1931 }
1932
1933 uint JumpProjNode::cmp( const Node &n ) const {
1934 return ProjNode::cmp(n) &&
1935 _dest_bci == ((JumpProjNode&)n)._dest_bci;
1936 }
1937
1938 #ifndef PRODUCT
1939 void JumpProjNode::dump_spec(outputStream *st) const {
1940 ProjNode::dump_spec(st);
1941 st->print("@bci %d ",_dest_bci);
1942 }
1943 #endif
1944
1945 //=============================================================================
1946 //------------------------------Value------------------------------------------
1947 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
1948 // have the default "fall_through_index" path.
1949 const Type *CatchNode::Value( PhaseTransform *phase ) const {
1950 // Unreachable? Then so are all paths from here.
1951 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
1952 // First assume all paths are reachable
1953 const Type** f = TypeTuple::fields(_size);
1954 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
1955 // Identify cases that will always throw an exception
1956 // () rethrow call
1957 // () virtual or interface call with NULL receiver
1958 // () call is a check cast with incompatible arguments
1959 if( in(1)->is_Proj() ) {
1960 Node *i10 = in(1)->in(0);
1961 if( i10->is_Call() ) {
1962 CallNode *call = i10->as_Call();
1963 // Rethrows always throw exceptions, never return
1964 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
1965 f[CatchProjNode::fall_through_index] = Type::TOP;
1966 } else if( call->req() > TypeFunc::Parms ) {
1967 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
1968 // Check for null receiver to virtual or interface calls
1969 if( call->is_CallDynamicJava() &&
1970 arg0->higher_equal(TypePtr::NULL_PTR) ) {
1971 f[CatchProjNode::fall_through_index] = Type::TOP;
1972 }
1973 } // End of if not a runtime stub
1974 } // End of if have call above me
1975 } // End of slot 1 is not a projection
1976 return TypeTuple::make(_size, f);
1977 }
1978
1979 //=============================================================================
1980 uint CatchProjNode::hash() const {
1981 return Node::hash() + _handler_bci;
1982 }
1983
1984
1985 uint CatchProjNode::cmp( const Node &n ) const {
1986 return ProjNode::cmp(n) &&
1987 _handler_bci == ((CatchProjNode&)n)._handler_bci;
1988 }
1989
1990
1991 //------------------------------Identity---------------------------------------
1992 // If only 1 target is possible, choose it if it is the main control
1993 Node *CatchProjNode::Identity( PhaseTransform *phase ) {
1994 // If my value is control and no other value is, then treat as ID
1995 const TypeTuple *t = phase->type(in(0))->is_tuple();
1996 if (t->field_at(_con) != Type::CONTROL) return this;
1997 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
1998 // also remove any exception table entry. Thus we must know the call
1999 // feeding the Catch will not really throw an exception. This is ok for
2000 // the main fall-thru control (happens when we know a call can never throw
2001 // an exception) or for "rethrow", because a further optimization will
2002 // yank the rethrow (happens when we inline a function that can throw an
2003 // exception and the caller has no handler). Not legal, e.g., for passing
2004 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2005 // These cases MUST throw an exception via the runtime system, so the VM
2006 // will be looking for a table entry.
2007 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2008 CallNode *call;
2009 if (_con != TypeFunc::Control && // Bail out if not the main control.
2010 !(proj->is_Proj() && // AND NOT a rethrow
2011 proj->in(0)->is_Call() &&
2012 (call = proj->in(0)->as_Call()) &&
2013 call->entry_point() == OptoRuntime::rethrow_stub()))
2014 return this;
2015
2016 // Search for any other path being control
2017 for (uint i = 0; i < t->cnt(); i++) {
2018 if (i != _con && t->field_at(i) == Type::CONTROL)
2019 return this;
2020 }
2021 // Only my path is possible; I am identity on control to the jump
2022 return in(0)->in(0);
2023 }
2024
2025
2026 #ifndef PRODUCT
2027 void CatchProjNode::dump_spec(outputStream *st) const {
2028 ProjNode::dump_spec(st);
2029 st->print("@bci %d ",_handler_bci);
2030 }
2031 #endif
2032
2033 //=============================================================================
2034 //------------------------------Identity---------------------------------------
2035 // Check for CreateEx being Identity.
2036 Node *CreateExNode::Identity( PhaseTransform *phase ) {
2037 if( phase->type(in(1)) == Type::TOP ) return in(1);
2038 if( phase->type(in(0)) == Type::TOP ) return in(0);
2039 // We only come from CatchProj, unless the CatchProj goes away.
2040 // If the CatchProj is optimized away, then we just carry the
2041 // exception oop through.
2042 CallNode *call = in(1)->in(0)->as_Call();
2043
2044 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2045 ? this
2046 : call->in(TypeFunc::Parms);
2047 }
2048
2049 //=============================================================================
2050 //------------------------------Value------------------------------------------
2051 // Check for being unreachable.
2052 const Type *NeverBranchNode::Value( PhaseTransform *phase ) const {
2053 if (!in(0) || in(0)->is_top()) return Type::TOP;
2054 return bottom_type();
2055 }
2056
2057 //------------------------------Ideal------------------------------------------
2058 // Check for no longer being part of a loop
2059 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2060 if (can_reshape && !in(0)->is_Loop()) {
2061 // Dead code elimination can sometimes delete this projection so
2062 // if it's not there, there's nothing to do.
2063 Node* fallthru = proj_out(0);
2064 if (fallthru != NULL) {
2065 phase->is_IterGVN()->subsume_node(fallthru, in(0));
2066 }
2067 return phase->C->top();
2068 }
2069 return NULL;
2070 }
2071
2072 #ifndef PRODUCT
2073 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2074 st->print("%s", Name());
2075 }
2076 #endif