1 /*
2 * Copyright (c) 1997, 2009, 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).
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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.
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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
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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->replace_node(n, top);
476 if( max != outcnt() ) {
477 progress = true;
478 j = refresh_out_pos(j);
479 max = outcnt();
480 }
481 }
482 }
483 }
484 add_to_worklist = true;
485 }
486 }
487 if (add_to_worklist) {
488 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
489 }
490
491 if( cnt <= 1 ) { // Only 1 path in?
492 set_req(0, NULL); // Null control input for region copy
493 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
494 // No inputs or all inputs are NULL.
495 return NULL;
496 } else if (can_reshape) { // Optimization phase - remove the node
497 PhaseIterGVN *igvn = phase->is_IterGVN();
498 Node *parent_ctrl;
499 if( cnt == 0 ) {
500 assert( req() == 1, "no inputs expected" );
501 // During IGVN phase such region will be subsumed by TOP node
502 // so region's phis will have TOP as control node.
503 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
504 // Also set other user's input to top.
505 parent_ctrl = phase->C->top();
506 } else {
507 // The fallthrough case since we already checked dead loops above.
508 parent_ctrl = in(1);
509 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
510 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
511 }
512 if (!add_to_worklist)
513 igvn->add_users_to_worklist(this); // Check for further allowed opts
514 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
515 Node* n = last_out(i);
516 igvn->hash_delete(n); // Remove from worklist before modifying edges
517 if( n->is_Phi() ) { // Collapse all Phis
518 // Eagerly replace phis to avoid copies generation.
519 Node* in;
520 if( cnt == 0 ) {
521 assert( n->req() == 1, "No data inputs expected" );
522 in = parent_ctrl; // replaced by top
523 } else {
524 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
525 in = n->in(1); // replaced by unique input
526 if( n->as_Phi()->is_unsafe_data_reference(in) )
527 in = phase->C->top(); // replaced by top
528 }
529 igvn->replace_node(n, in);
530 }
531 else if( n->is_Region() ) { // Update all incoming edges
532 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
533 uint uses_found = 0;
534 for( uint k=1; k < n->req(); k++ ) {
535 if( n->in(k) == this ) {
536 n->set_req(k, parent_ctrl);
537 uses_found++;
538 }
539 }
540 if( uses_found > 1 ) { // (--i) done at the end of the loop.
541 i -= (uses_found - 1);
542 }
543 }
544 else {
545 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
546 n->set_req(0, parent_ctrl);
547 }
548 #ifdef ASSERT
549 for( uint k=0; k < n->req(); k++ ) {
550 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
551 }
552 #endif
553 }
554 // Remove the RegionNode itself from DefUse info
555 igvn->remove_dead_node(this);
556 return NULL;
557 }
558 return this; // Record progress
559 }
560
561
562 // If a Region flows into a Region, merge into one big happy merge.
563 if (can_reshape) {
564 Node *m = merge_region(this, phase);
565 if (m != NULL) return m;
566 }
567
568 // Check if this region is the root of a clipping idiom on floats
569 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
570 // Check that only one use is a Phi and that it simplifies to two constants +
571 PhiNode* phi = has_unique_phi();
572 if (phi != NULL) { // One Phi user
573 // Check inputs to the Phi
574 ConNode *min;
575 ConNode *max;
576 Node *val;
577 uint min_idx;
578 uint max_idx;
579 uint val_idx;
580 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
581 IfNode *top_if;
582 IfNode *bot_if;
583 if( check_if_clipping( this, bot_if, top_if ) ) {
584 // Control pattern checks, now verify compares
585 Node *top_in = NULL; // value being compared against
586 Node *bot_in = NULL;
587 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
588 check_compare_clipping( false, top_if, max, top_in ) ) {
589 if( bot_in == top_in ) {
590 PhaseIterGVN *gvn = phase->is_IterGVN();
591 assert( gvn != NULL, "Only had DefUse info in IterGVN");
592 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
593
594 // Check for the ConvF2INode
595 ConvF2INode *convf2i;
596 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
597 convf2i->in(1) == bot_in ) {
598 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
599 // max test
600 Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, min ));
601 Node *boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::lt ));
602 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 ));
603 Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
604 Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
605 // min test
606 cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, max ));
607 boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::gt ));
608 iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
609 Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
610 ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
611 // update input edges to region node
612 set_req_X( min_idx, if_min, gvn );
613 set_req_X( max_idx, if_max, gvn );
614 set_req_X( val_idx, ifF, gvn );
615 // remove unnecessary 'LShiftI; RShiftI' idiom
616 gvn->hash_delete(phi);
617 phi->set_req_X( val_idx, convf2i, gvn );
618 gvn->hash_find_insert(phi);
619 // Return transformed region node
620 return this;
621 }
622 }
623 }
624 }
625 }
626 }
627 }
628
629 return NULL;
630 }
631
632
633
634 const RegMask &RegionNode::out_RegMask() const {
635 return RegMask::Empty;
636 }
637
638 // Find the one non-null required input. RegionNode only
639 Node *Node::nonnull_req() const {
640 assert( is_Region(), "" );
641 for( uint i = 1; i < _cnt; i++ )
642 if( in(i) )
643 return in(i);
644 ShouldNotReachHere();
645 return NULL;
646 }
647
648
649 //=============================================================================
650 // note that these functions assume that the _adr_type field is flattened
651 uint PhiNode::hash() const {
652 const Type* at = _adr_type;
653 return TypeNode::hash() + (at ? at->hash() : 0);
654 }
655 uint PhiNode::cmp( const Node &n ) const {
656 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
657 }
658 static inline
659 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
660 if (at == NULL || at == TypePtr::BOTTOM) return at;
661 return Compile::current()->alias_type(at)->adr_type();
662 }
663
664 //----------------------------make---------------------------------------------
665 // create a new phi with edges matching r and set (initially) to x
666 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
667 uint preds = r->req(); // Number of predecessor paths
668 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
669 PhiNode* p = new (Compile::current(), preds) PhiNode(r, t, at);
670 for (uint j = 1; j < preds; j++) {
671 // Fill in all inputs, except those which the region does not yet have
672 if (r->in(j) != NULL)
673 p->init_req(j, x);
674 }
675 return p;
676 }
677 PhiNode* PhiNode::make(Node* r, Node* x) {
678 const Type* t = x->bottom_type();
679 const TypePtr* at = NULL;
680 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
681 return make(r, x, t, at);
682 }
683 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
684 const Type* t = x->bottom_type();
685 const TypePtr* at = NULL;
686 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
687 return new (Compile::current(), r->req()) PhiNode(r, t, at);
688 }
689
690
691 //------------------------slice_memory-----------------------------------------
692 // create a new phi with narrowed memory type
693 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
694 PhiNode* mem = (PhiNode*) clone();
695 *(const TypePtr**)&mem->_adr_type = adr_type;
696 // convert self-loops, or else we get a bad graph
697 for (uint i = 1; i < req(); i++) {
698 if ((const Node*)in(i) == this) mem->set_req(i, mem);
699 }
700 mem->verify_adr_type();
701 return mem;
702 }
703
704 //------------------------split_out_instance-----------------------------------
705 // Split out an instance type from a bottom phi.
706 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
707 const TypeOopPtr *t_oop = at->isa_oopptr();
708 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
709 const TypePtr *t = adr_type();
710 assert(type() == Type::MEMORY &&
711 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
712 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
713 t->is_oopptr()->cast_to_exactness(true)
714 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
715 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
716 "bottom or raw memory required");
717
718 // Check if an appropriate node already exists.
719 Node *region = in(0);
720 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
721 Node* use = region->fast_out(k);
722 if( use->is_Phi()) {
723 PhiNode *phi2 = use->as_Phi();
724 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
725 return phi2;
726 }
727 }
728 }
729 Compile *C = igvn->C;
730 Arena *a = Thread::current()->resource_area();
731 Node_Array node_map = new Node_Array(a);
732 Node_Stack stack(a, C->unique() >> 4);
733 PhiNode *nphi = slice_memory(at);
734 igvn->register_new_node_with_optimizer( nphi );
735 node_map.map(_idx, nphi);
736 stack.push((Node *)this, 1);
737 while(!stack.is_empty()) {
738 PhiNode *ophi = stack.node()->as_Phi();
739 uint i = stack.index();
740 assert(i >= 1, "not control edge");
741 stack.pop();
742 nphi = node_map[ophi->_idx]->as_Phi();
743 for (; i < ophi->req(); i++) {
744 Node *in = ophi->in(i);
745 if (in == NULL || igvn->type(in) == Type::TOP)
746 continue;
747 Node *opt = MemNode::optimize_simple_memory_chain(in, at, igvn);
748 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
749 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
750 opt = node_map[optphi->_idx];
751 if (opt == NULL) {
752 stack.push(ophi, i);
753 nphi = optphi->slice_memory(at);
754 igvn->register_new_node_with_optimizer( nphi );
755 node_map.map(optphi->_idx, nphi);
756 ophi = optphi;
757 i = 0; // will get incremented at top of loop
758 continue;
759 }
760 }
761 nphi->set_req(i, opt);
762 }
763 }
764 return nphi;
765 }
766
767 //------------------------verify_adr_type--------------------------------------
768 #ifdef ASSERT
769 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
770 if (visited.test_set(_idx)) return; //already visited
771
772 // recheck constructor invariants:
773 verify_adr_type(false);
774
775 // recheck local phi/phi consistency:
776 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
777 "adr_type must be consistent across phi nest");
778
779 // walk around
780 for (uint i = 1; i < req(); i++) {
781 Node* n = in(i);
782 if (n == NULL) continue;
783 const Node* np = in(i);
784 if (np->is_Phi()) {
785 np->as_Phi()->verify_adr_type(visited, at);
786 } else if (n->bottom_type() == Type::TOP
787 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
788 // ignore top inputs
789 } else {
790 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
791 // recheck phi/non-phi consistency at leaves:
792 assert((nat != NULL) == (at != NULL), "");
793 assert(nat == at || nat == TypePtr::BOTTOM,
794 "adr_type must be consistent at leaves of phi nest");
795 }
796 }
797 }
798
799 // Verify a whole nest of phis rooted at this one.
800 void PhiNode::verify_adr_type(bool recursive) const {
801 if (is_error_reported()) return; // muzzle asserts when debugging an error
802 if (Node::in_dump()) return; // muzzle asserts when printing
803
804 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
805
806 if (!VerifyAliases) return; // verify thoroughly only if requested
807
808 assert(_adr_type == flatten_phi_adr_type(_adr_type),
809 "Phi::adr_type must be pre-normalized");
810
811 if (recursive) {
812 VectorSet visited(Thread::current()->resource_area());
813 verify_adr_type(visited, _adr_type);
814 }
815 }
816 #endif
817
818
819 //------------------------------Value------------------------------------------
820 // Compute the type of the PhiNode
821 const Type *PhiNode::Value( PhaseTransform *phase ) const {
822 Node *r = in(0); // RegionNode
823 if( !r ) // Copy or dead
824 return in(1) ? phase->type(in(1)) : Type::TOP;
825
826 // Note: During parsing, phis are often transformed before their regions.
827 // This means we have to use type_or_null to defend against untyped regions.
828 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
829 return Type::TOP;
830
831 // Check for trip-counted loop. If so, be smarter.
832 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
833 if( l && l->can_be_counted_loop(phase) &&
834 ((const Node*)l->phi() == this) ) { // Trip counted loop!
835 // protect against init_trip() or limit() returning NULL
836 const Node *init = l->init_trip();
837 const Node *limit = l->limit();
838 if( init != NULL && limit != NULL && l->stride_is_con() ) {
839 const TypeInt *lo = init ->bottom_type()->isa_int();
840 const TypeInt *hi = limit->bottom_type()->isa_int();
841 if( lo && hi ) { // Dying loops might have TOP here
842 int stride = l->stride_con();
843 if( stride < 0 ) { // Down-counter loop
844 const TypeInt *tmp = lo; lo = hi; hi = tmp;
845 stride = -stride;
846 }
847 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
848 return TypeInt::make(lo->_lo,hi->_hi,3);
849 }
850 }
851 }
852
853 // Until we have harmony between classes and interfaces in the type
854 // lattice, we must tread carefully around phis which implicitly
855 // convert the one to the other.
856 const TypePtr* ttp = _type->make_ptr();
857 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
858 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
859 bool is_intf = false;
860 if (ttip != NULL) {
861 ciKlass* k = ttip->klass();
862 if (k->is_loaded() && k->is_interface())
863 is_intf = true;
864 }
865 if (ttkp != NULL) {
866 ciKlass* k = ttkp->klass();
867 if (k->is_loaded() && k->is_interface())
868 is_intf = true;
869 }
870
871 // Default case: merge all inputs
872 const Type *t = Type::TOP; // Merged type starting value
873 for (uint i = 1; i < req(); ++i) {// For all paths in
874 // Reachable control path?
875 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
876 const Type* ti = phase->type(in(i));
877 // We assume that each input of an interface-valued Phi is a true
878 // subtype of that interface. This might not be true of the meet
879 // of all the input types. The lattice is not distributive in
880 // such cases. Ward off asserts in type.cpp by refusing to do
881 // meets between interfaces and proper classes.
882 const TypePtr* tip = ti->make_ptr();
883 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
884 if (tiip) {
885 bool ti_is_intf = false;
886 ciKlass* k = tiip->klass();
887 if (k->is_loaded() && k->is_interface())
888 ti_is_intf = true;
889 if (is_intf != ti_is_intf)
890 { t = _type; break; }
891 }
892 t = t->meet(ti);
893 }
894 }
895
896 // The worst-case type (from ciTypeFlow) should be consistent with "t".
897 // That is, we expect that "t->higher_equal(_type)" holds true.
898 // There are various exceptions:
899 // - Inputs which are phis might in fact be widened unnecessarily.
900 // For example, an input might be a widened int while the phi is a short.
901 // - Inputs might be BotPtrs but this phi is dependent on a null check,
902 // and postCCP has removed the cast which encodes the result of the check.
903 // - The type of this phi is an interface, and the inputs are classes.
904 // - Value calls on inputs might produce fuzzy results.
905 // (Occurrences of this case suggest improvements to Value methods.)
906 //
907 // It is not possible to see Type::BOTTOM values as phi inputs,
908 // because the ciTypeFlow pre-pass produces verifier-quality types.
909 const Type* ft = t->filter(_type); // Worst case type
910
911 #ifdef ASSERT
912 // The following logic has been moved into TypeOopPtr::filter.
913 const Type* jt = t->join(_type);
914 if( jt->empty() ) { // Emptied out???
915
916 // Check for evil case of 't' being a class and '_type' expecting an
917 // interface. This can happen because the bytecodes do not contain
918 // enough type info to distinguish a Java-level interface variable
919 // from a Java-level object variable. If we meet 2 classes which
920 // both implement interface I, but their meet is at 'j/l/O' which
921 // doesn't implement I, we have no way to tell if the result should
922 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
923 // into a Phi which "knows" it's an Interface type we'll have to
924 // uplift the type.
925 if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() )
926 { assert(ft == _type, ""); } // Uplift to interface
927 else if( !t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface() )
928 { assert(ft == _type, ""); } // Uplift to interface
929 // Otherwise it's something stupid like non-overlapping int ranges
930 // found on dying counted loops.
931 else
932 { assert(ft == Type::TOP, ""); } // Canonical empty value
933 }
934
935 else {
936
937 // If we have an interface-typed Phi and we narrow to a class type, the join
938 // should report back the class. However, if we have a J/L/Object
939 // class-typed Phi and an interface flows in, it's possible that the meet &
940 // join report an interface back out. This isn't possible but happens
941 // because the type system doesn't interact well with interfaces.
942 const TypePtr *jtp = jt->make_ptr();
943 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
944 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
945 if( jtip && ttip ) {
946 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
947 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
948 // Happens in a CTW of rt.jar, 320-341, no extra flags
949 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
950 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
951 jt = ft;
952 }
953 }
954 if( jtkp && ttkp ) {
955 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
956 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
957 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
958 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
959 ft->isa_narrowoop() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
960 jt = ft;
961 }
962 }
963 if (jt != ft && jt->base() == ft->base()) {
964 if (jt->isa_int() &&
965 jt->is_int()->_lo == ft->is_int()->_lo &&
966 jt->is_int()->_hi == ft->is_int()->_hi)
967 jt = ft;
968 if (jt->isa_long() &&
969 jt->is_long()->_lo == ft->is_long()->_lo &&
970 jt->is_long()->_hi == ft->is_long()->_hi)
971 jt = ft;
972 }
973 if (jt != ft) {
974 tty->print("merge type: "); t->dump(); tty->cr();
975 tty->print("kill type: "); _type->dump(); tty->cr();
976 tty->print("join type: "); jt->dump(); tty->cr();
977 tty->print("filter type: "); ft->dump(); tty->cr();
978 }
979 assert(jt == ft, "");
980 }
981 #endif //ASSERT
982
983 // Deal with conversion problems found in data loops.
984 ft = phase->saturate(ft, phase->type_or_null(this), _type);
985
986 return ft;
987 }
988
989
990 //------------------------------is_diamond_phi---------------------------------
991 // Does this Phi represent a simple well-shaped diamond merge? Return the
992 // index of the true path or 0 otherwise.
993 int PhiNode::is_diamond_phi() const {
994 // Check for a 2-path merge
995 Node *region = in(0);
996 if( !region ) return 0;
997 if( region->req() != 3 ) return 0;
998 if( req() != 3 ) return 0;
999 // Check that both paths come from the same If
1000 Node *ifp1 = region->in(1);
1001 Node *ifp2 = region->in(2);
1002 if( !ifp1 || !ifp2 ) return 0;
1003 Node *iff = ifp1->in(0);
1004 if( !iff || !iff->is_If() ) return 0;
1005 if( iff != ifp2->in(0) ) return 0;
1006 // Check for a proper bool/cmp
1007 const Node *b = iff->in(1);
1008 if( !b->is_Bool() ) return 0;
1009 const Node *cmp = b->in(1);
1010 if( !cmp->is_Cmp() ) return 0;
1011
1012 // Check for branching opposite expected
1013 if( ifp2->Opcode() == Op_IfTrue ) {
1014 assert( ifp1->Opcode() == Op_IfFalse, "" );
1015 return 2;
1016 } else {
1017 assert( ifp1->Opcode() == Op_IfTrue, "" );
1018 return 1;
1019 }
1020 }
1021
1022 //----------------------------check_cmove_id-----------------------------------
1023 // Check for CMove'ing a constant after comparing against the constant.
1024 // Happens all the time now, since if we compare equality vs a constant in
1025 // the parser, we "know" the variable is constant on one path and we force
1026 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1027 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1028 // general in that we don't need constants. Since CMove's are only inserted
1029 // in very special circumstances, we do it here on generic Phi's.
1030 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1031 assert(true_path !=0, "only diamond shape graph expected");
1032
1033 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1034 // phi->region->if_proj->ifnode->bool->cmp
1035 Node* region = in(0);
1036 Node* iff = region->in(1)->in(0);
1037 BoolNode* b = iff->in(1)->as_Bool();
1038 Node* cmp = b->in(1);
1039 Node* tval = in(true_path);
1040 Node* fval = in(3-true_path);
1041 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1042 if (id == NULL)
1043 return NULL;
1044
1045 // Either value might be a cast that depends on a branch of 'iff'.
1046 // Since the 'id' value will float free of the diamond, either
1047 // decast or return failure.
1048 Node* ctl = id->in(0);
1049 if (ctl != NULL && ctl->in(0) == iff) {
1050 if (id->is_ConstraintCast()) {
1051 return id->in(1);
1052 } else {
1053 // Don't know how to disentangle this value.
1054 return NULL;
1055 }
1056 }
1057
1058 return id;
1059 }
1060
1061 //------------------------------Identity---------------------------------------
1062 // Check for Region being Identity.
1063 Node *PhiNode::Identity( PhaseTransform *phase ) {
1064 // Check for no merging going on
1065 // (There used to be special-case code here when this->region->is_Loop.
1066 // It would check for a tributary phi on the backedge that the main phi
1067 // trivially, perhaps with a single cast. The unique_input method
1068 // does all this and more, by reducing such tributaries to 'this'.)
1069 Node* uin = unique_input(phase);
1070 if (uin != NULL) {
1071 return uin;
1072 }
1073
1074 int true_path = is_diamond_phi();
1075 if (true_path != 0) {
1076 Node* id = is_cmove_id(phase, true_path);
1077 if (id != NULL) return id;
1078 }
1079
1080 return this; // No identity
1081 }
1082
1083 //-----------------------------unique_input------------------------------------
1084 // Find the unique value, discounting top, self-loops, and casts.
1085 // Return top if there are no inputs, and self if there are multiple.
1086 Node* PhiNode::unique_input(PhaseTransform* phase) {
1087 // 1) One unique direct input, or
1088 // 2) some of the inputs have an intervening ConstraintCast and
1089 // the type of input is the same or sharper (more specific)
1090 // than the phi's type.
1091 // 3) an input is a self loop
1092 //
1093 // 1) input or 2) input or 3) input __
1094 // / \ / \ \ / \
1095 // \ / | cast phi cast
1096 // phi \ / / \ /
1097 // phi / --
1098
1099 Node* r = in(0); // RegionNode
1100 if (r == NULL) return in(1); // Already degraded to a Copy
1101 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
1102 Node* direct_input = NULL; // The unique direct input
1103
1104 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1105 Node* rc = r->in(i);
1106 if (rc == NULL || phase->type(rc) == Type::TOP)
1107 continue; // ignore unreachable control path
1108 Node* n = in(i);
1109 if (n == NULL)
1110 continue;
1111 Node* un = n->uncast();
1112 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1113 continue; // ignore if top, or in(i) and "this" are in a data cycle
1114 }
1115 // Check for a unique uncasted input
1116 if (uncasted_input == NULL) {
1117 uncasted_input = un;
1118 } else if (uncasted_input != un) {
1119 uncasted_input = NodeSentinel; // no unique uncasted input
1120 }
1121 // Check for a unique direct input
1122 if (direct_input == NULL) {
1123 direct_input = n;
1124 } else if (direct_input != n) {
1125 direct_input = NodeSentinel; // no unique direct input
1126 }
1127 }
1128 if (direct_input == NULL) {
1129 return phase->C->top(); // no inputs
1130 }
1131 assert(uncasted_input != NULL,"");
1132
1133 if (direct_input != NodeSentinel) {
1134 return direct_input; // one unique direct input
1135 }
1136 if (uncasted_input != NodeSentinel &&
1137 phase->type(uncasted_input)->higher_equal(type())) {
1138 return uncasted_input; // one unique uncasted input
1139 }
1140
1141 // Nothing.
1142 return NULL;
1143 }
1144
1145 //------------------------------is_x2logic-------------------------------------
1146 // Check for simple convert-to-boolean pattern
1147 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1148 // Convert Phi to an ConvIB.
1149 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1150 assert(true_path !=0, "only diamond shape graph expected");
1151 // Convert the true/false index into an expected 0/1 return.
1152 // Map 2->0 and 1->1.
1153 int flipped = 2-true_path;
1154
1155 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1156 // phi->region->if_proj->ifnode->bool->cmp
1157 Node *region = phi->in(0);
1158 Node *iff = region->in(1)->in(0);
1159 BoolNode *b = (BoolNode*)iff->in(1);
1160 const CmpNode *cmp = (CmpNode*)b->in(1);
1161
1162 Node *zero = phi->in(1);
1163 Node *one = phi->in(2);
1164 const Type *tzero = phase->type( zero );
1165 const Type *tone = phase->type( one );
1166
1167 // Check for compare vs 0
1168 const Type *tcmp = phase->type(cmp->in(2));
1169 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1170 // Allow cmp-vs-1 if the other input is bounded by 0-1
1171 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1172 return NULL;
1173 flipped = 1-flipped; // Test is vs 1 instead of 0!
1174 }
1175
1176 // Check for setting zero/one opposite expected
1177 if( tzero == TypeInt::ZERO ) {
1178 if( tone == TypeInt::ONE ) {
1179 } else return NULL;
1180 } else if( tzero == TypeInt::ONE ) {
1181 if( tone == TypeInt::ZERO ) {
1182 flipped = 1-flipped;
1183 } else return NULL;
1184 } else return NULL;
1185
1186 // Check for boolean test backwards
1187 if( b->_test._test == BoolTest::ne ) {
1188 } else if( b->_test._test == BoolTest::eq ) {
1189 flipped = 1-flipped;
1190 } else return NULL;
1191
1192 // Build int->bool conversion
1193 Node *n = new (phase->C, 2) Conv2BNode( cmp->in(1) );
1194 if( flipped )
1195 n = new (phase->C, 3) XorINode( phase->transform(n), phase->intcon(1) );
1196
1197 return n;
1198 }
1199
1200 //------------------------------is_cond_add------------------------------------
1201 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1202 // To be profitable the control flow has to disappear; there can be no other
1203 // values merging here. We replace the test-and-branch with:
1204 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1205 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1206 // Then convert Y to 0-or-Y and finally add.
1207 // This is a key transform for SpecJava _201_compress.
1208 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1209 assert(true_path !=0, "only diamond shape graph expected");
1210
1211 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1212 // phi->region->if_proj->ifnode->bool->cmp
1213 RegionNode *region = (RegionNode*)phi->in(0);
1214 Node *iff = region->in(1)->in(0);
1215 BoolNode* b = iff->in(1)->as_Bool();
1216 const CmpNode *cmp = (CmpNode*)b->in(1);
1217
1218 // Make sure only merging this one phi here
1219 if (region->has_unique_phi() != phi) return NULL;
1220
1221 // Make sure each arm of the diamond has exactly one output, which we assume
1222 // is the region. Otherwise, the control flow won't disappear.
1223 if (region->in(1)->outcnt() != 1) return NULL;
1224 if (region->in(2)->outcnt() != 1) return NULL;
1225
1226 // Check for "(P < Q)" of type signed int
1227 if (b->_test._test != BoolTest::lt) return NULL;
1228 if (cmp->Opcode() != Op_CmpI) return NULL;
1229
1230 Node *p = cmp->in(1);
1231 Node *q = cmp->in(2);
1232 Node *n1 = phi->in( true_path);
1233 Node *n2 = phi->in(3-true_path);
1234
1235 int op = n1->Opcode();
1236 if( op != Op_AddI // Need zero as additive identity
1237 /*&&op != Op_SubI &&
1238 op != Op_AddP &&
1239 op != Op_XorI &&
1240 op != Op_OrI*/ )
1241 return NULL;
1242
1243 Node *x = n2;
1244 Node *y = n1->in(1);
1245 if( n2 == n1->in(1) ) {
1246 y = n1->in(2);
1247 } else if( n2 == n1->in(1) ) {
1248 } else return NULL;
1249
1250 // Not so profitable if compare and add are constants
1251 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1252 return NULL;
1253
1254 Node *cmplt = phase->transform( new (phase->C, 3) CmpLTMaskNode(p,q) );
1255 Node *j_and = phase->transform( new (phase->C, 3) AndINode(cmplt,y) );
1256 return new (phase->C, 3) AddINode(j_and,x);
1257 }
1258
1259 //------------------------------is_absolute------------------------------------
1260 // Check for absolute value.
1261 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1262 assert(true_path !=0, "only diamond shape graph expected");
1263
1264 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1265 int phi_x_idx = 0; // Index of phi input where to find naked x
1266
1267 // ABS ends with the merge of 2 control flow paths.
1268 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1269 int false_path = 3 - true_path;
1270
1271 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1272 // phi->region->if_proj->ifnode->bool->cmp
1273 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1274
1275 // Check bool sense
1276 switch( bol->_test._test ) {
1277 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1278 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1279 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1280 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1281 default: return NULL; break;
1282 }
1283
1284 // Test is next
1285 Node *cmp = bol->in(1);
1286 const Type *tzero = NULL;
1287 switch( cmp->Opcode() ) {
1288 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1289 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1290 default: return NULL;
1291 }
1292
1293 // Find zero input of compare; the other input is being abs'd
1294 Node *x = NULL;
1295 bool flip = false;
1296 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1297 x = cmp->in(3 - cmp_zero_idx);
1298 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1299 // The test is inverted, we should invert the result...
1300 x = cmp->in(cmp_zero_idx);
1301 flip = true;
1302 } else {
1303 return NULL;
1304 }
1305
1306 // Next get the 2 pieces being selected, one is the original value
1307 // and the other is the negated value.
1308 if( phi_root->in(phi_x_idx) != x ) return NULL;
1309
1310 // Check other phi input for subtract node
1311 Node *sub = phi_root->in(3 - phi_x_idx);
1312
1313 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1314 if( tzero == TypeF::ZERO ) {
1315 if( sub->Opcode() != Op_SubF ||
1316 sub->in(2) != x ||
1317 phase->type(sub->in(1)) != tzero ) return NULL;
1318 x = new (phase->C, 2) AbsFNode(x);
1319 if (flip) {
1320 x = new (phase->C, 3) SubFNode(sub->in(1), phase->transform(x));
1321 }
1322 } else {
1323 if( sub->Opcode() != Op_SubD ||
1324 sub->in(2) != x ||
1325 phase->type(sub->in(1)) != tzero ) return NULL;
1326 x = new (phase->C, 2) AbsDNode(x);
1327 if (flip) {
1328 x = new (phase->C, 3) SubDNode(sub->in(1), phase->transform(x));
1329 }
1330 }
1331
1332 return x;
1333 }
1334
1335 //------------------------------split_once-------------------------------------
1336 // Helper for split_flow_path
1337 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1338 igvn->hash_delete(n); // Remove from hash before hacking edges
1339
1340 uint j = 1;
1341 for( uint i = phi->req()-1; i > 0; i-- ) {
1342 if( phi->in(i) == val ) { // Found a path with val?
1343 // Add to NEW Region/Phi, no DU info
1344 newn->set_req( j++, n->in(i) );
1345 // Remove from OLD Region/Phi
1346 n->del_req(i);
1347 }
1348 }
1349
1350 // Register the new node but do not transform it. Cannot transform until the
1351 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1352 igvn->register_new_node_with_optimizer( newn );
1353 // Now I can point to the new node.
1354 n->add_req(newn);
1355 igvn->_worklist.push(n);
1356 }
1357
1358 //------------------------------split_flow_path--------------------------------
1359 // Check for merging identical values and split flow paths
1360 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1361 BasicType bt = phi->type()->basic_type();
1362 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1363 return NULL; // Bail out on funny non-value stuff
1364 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1365 return NULL; // third unequal input to be worth doing
1366
1367 // Scan for a constant
1368 uint i;
1369 for( i = 1; i < phi->req()-1; i++ ) {
1370 Node *n = phi->in(i);
1371 if( !n ) return NULL;
1372 if( phase->type(n) == Type::TOP ) return NULL;
1373 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN )
1374 break;
1375 }
1376 if( i >= phi->req() ) // Only split for constants
1377 return NULL;
1378
1379 Node *val = phi->in(i); // Constant to split for
1380 uint hit = 0; // Number of times it occurs
1381
1382 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1383 Node *n = phi->in(i);
1384 if( !n ) return NULL;
1385 if( phase->type(n) == Type::TOP ) return NULL;
1386 if( phi->in(i) == val )
1387 hit++;
1388 }
1389
1390 if( hit <= 1 || // Make sure we find 2 or more
1391 hit == phi->req()-1 ) // and not ALL the same value
1392 return NULL;
1393
1394 // Now start splitting out the flow paths that merge the same value.
1395 // Split first the RegionNode.
1396 PhaseIterGVN *igvn = phase->is_IterGVN();
1397 Node *r = phi->region();
1398 RegionNode *newr = new (phase->C, hit+1) RegionNode(hit+1);
1399 split_once(igvn, phi, val, r, newr);
1400
1401 // Now split all other Phis than this one
1402 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1403 Node* phi2 = r->fast_out(k);
1404 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1405 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1406 split_once(igvn, phi, val, phi2, newphi);
1407 }
1408 }
1409
1410 // Clean up this guy
1411 igvn->hash_delete(phi);
1412 for( i = phi->req()-1; i > 0; i-- ) {
1413 if( phi->in(i) == val ) {
1414 phi->del_req(i);
1415 }
1416 }
1417 phi->add_req(val);
1418
1419 return phi;
1420 }
1421
1422 //=============================================================================
1423 //------------------------------simple_data_loop_check-------------------------
1424 // Try to determining if the phi node in a simple safe/unsafe data loop.
1425 // Returns:
1426 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1427 // Safe - safe case when the phi and it's inputs reference only safe data
1428 // nodes;
1429 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1430 // is no reference back to the phi - need a graph walk
1431 // to determine if it is in a loop;
1432 // UnsafeLoop - unsafe case when the phi references itself directly or through
1433 // unsafe data node.
1434 // Note: a safe data node is a node which could/never reference itself during
1435 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1436 // I mark Phi nodes as safe node not only because they can reference itself
1437 // but also to prevent mistaking the fallthrough case inside an outer loop
1438 // as dead loop when the phi references itselfs through an other phi.
1439 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1440 // It is unsafe loop if the phi node references itself directly.
1441 if (in == (Node*)this)
1442 return UnsafeLoop; // Unsafe loop
1443 // Unsafe loop if the phi node references itself through an unsafe data node.
1444 // Exclude cases with null inputs or data nodes which could reference
1445 // itself (safe for dead loops).
1446 if (in != NULL && !in->is_dead_loop_safe()) {
1447 // Check inputs of phi's inputs also.
1448 // It is much less expensive then full graph walk.
1449 uint cnt = in->req();
1450 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1451 for (; i < cnt; ++i) {
1452 Node* m = in->in(i);
1453 if (m == (Node*)this)
1454 return UnsafeLoop; // Unsafe loop
1455 if (m != NULL && !m->is_dead_loop_safe()) {
1456 // Check the most common case (about 30% of all cases):
1457 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1458 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1459 if (m1 == (Node*)this)
1460 return UnsafeLoop; // Unsafe loop
1461 if (m1 != NULL && m1 == m->in(2) &&
1462 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1463 continue; // Safe case
1464 }
1465 // The phi references an unsafe node - need full analysis.
1466 return Unsafe;
1467 }
1468 }
1469 }
1470 return Safe; // Safe case - we can optimize the phi node.
1471 }
1472
1473 //------------------------------is_unsafe_data_reference-----------------------
1474 // If phi can be reached through the data input - it is data loop.
1475 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1476 assert(req() > 1, "");
1477 // First, check simple cases when phi references itself directly or
1478 // through an other node.
1479 LoopSafety safety = simple_data_loop_check(in);
1480 if (safety == UnsafeLoop)
1481 return true; // phi references itself - unsafe loop
1482 else if (safety == Safe)
1483 return false; // Safe case - phi could be replaced with the unique input.
1484
1485 // Unsafe case when we should go through data graph to determine
1486 // if the phi references itself.
1487
1488 ResourceMark rm;
1489
1490 Arena *a = Thread::current()->resource_area();
1491 Node_List nstack(a);
1492 VectorSet visited(a);
1493
1494 nstack.push(in); // Start with unique input.
1495 visited.set(in->_idx);
1496 while (nstack.size() != 0) {
1497 Node* n = nstack.pop();
1498 uint cnt = n->req();
1499 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1500 for (; i < cnt; i++) {
1501 Node* m = n->in(i);
1502 if (m == (Node*)this) {
1503 return true; // Data loop
1504 }
1505 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1506 if (!visited.test_set(m->_idx))
1507 nstack.push(m);
1508 }
1509 }
1510 }
1511 return false; // The phi is not reachable from its inputs
1512 }
1513
1514
1515 //------------------------------Ideal------------------------------------------
1516 // Return a node which is more "ideal" than the current node. Must preserve
1517 // the CFG, but we can still strip out dead paths.
1518 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1519 // The next should never happen after 6297035 fix.
1520 if( is_copy() ) // Already degraded to a Copy ?
1521 return NULL; // No change
1522
1523 Node *r = in(0); // RegionNode
1524 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1525
1526 // Note: During parsing, phis are often transformed before their regions.
1527 // This means we have to use type_or_null to defend against untyped regions.
1528 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1529 return NULL; // No change
1530
1531 Node *top = phase->C->top();
1532 bool new_phi = (outcnt() == 0); // transforming new Phi
1533 assert(!can_reshape || !new_phi, "for igvn new phi should be hooked");
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 if (can_reshape && outcnt() == 0) {
1554 // set_req() above may kill outputs if Phi is referenced
1555 // only by itself on the dead (top) control path.
1556 return top;
1557 }
1558
1559 Node* uin = unique_input(phase);
1560 if (uin == top) { // Simplest case: no alive inputs.
1561 if (can_reshape) // IGVN transformation
1562 return top;
1563 else
1564 return NULL; // Identity will return TOP
1565 } else if (uin != NULL) {
1566 // Only one not-NULL unique input path is left.
1567 // Determine if this input is backedge of a loop.
1568 // (Skip new phis which have no uses and dead regions).
1569 if( outcnt() > 0 && r->in(0) != NULL ) {
1570 // First, take the short cut when we know it is a loop and
1571 // the EntryControl data path is dead.
1572 assert(!r->is_Loop() || r->req() == 3, "Loop node should have 3 inputs");
1573 // Then, check if there is a data loop when phi references itself directly
1574 // or through other data nodes.
1575 if( r->is_Loop() && !phase->eqv_uncast(uin, in(LoopNode::EntryControl)) ||
1576 !r->is_Loop() && is_unsafe_data_reference(uin) ) {
1577 // Break this data loop to avoid creation of a dead loop.
1578 if (can_reshape) {
1579 return top;
1580 } else {
1581 // We can't return top if we are in Parse phase - cut inputs only
1582 // let Identity to handle the case.
1583 replace_edge(uin, top);
1584 return NULL;
1585 }
1586 }
1587 }
1588
1589 // One unique input.
1590 debug_only(Node* ident = Identity(phase));
1591 // The unique input must eventually be detected by the Identity call.
1592 #ifdef ASSERT
1593 if (ident != uin && !ident->is_top()) {
1594 // print this output before failing assert
1595 r->dump(3);
1596 this->dump(3);
1597 ident->dump();
1598 uin->dump();
1599 }
1600 #endif
1601 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1602 return NULL;
1603 }
1604
1605
1606 Node* opt = NULL;
1607 int true_path = is_diamond_phi();
1608 if( true_path != 0 ) {
1609 // Check for CMove'ing identity. If it would be unsafe,
1610 // handle it here. In the safe case, let Identity handle it.
1611 Node* unsafe_id = is_cmove_id(phase, true_path);
1612 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1613 opt = unsafe_id;
1614
1615 // Check for simple convert-to-boolean pattern
1616 if( opt == NULL )
1617 opt = is_x2logic(phase, this, true_path);
1618
1619 // Check for absolute value
1620 if( opt == NULL )
1621 opt = is_absolute(phase, this, true_path);
1622
1623 // Check for conditional add
1624 if( opt == NULL && can_reshape )
1625 opt = is_cond_add(phase, this, true_path);
1626
1627 // These 4 optimizations could subsume the phi:
1628 // have to check for a dead data loop creation.
1629 if( opt != NULL ) {
1630 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1631 // Found dead loop.
1632 if( can_reshape )
1633 return top;
1634 // We can't return top if we are in Parse phase - cut inputs only
1635 // to stop further optimizations for this phi. Identity will return TOP.
1636 assert(req() == 3, "only diamond merge phi here");
1637 set_req(1, top);
1638 set_req(2, top);
1639 return NULL;
1640 } else {
1641 return opt;
1642 }
1643 }
1644 }
1645
1646 // Check for merging identical values and split flow paths
1647 if (can_reshape) {
1648 opt = split_flow_path(phase, this);
1649 // This optimization only modifies phi - don't need to check for dead loop.
1650 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1651 if (opt != NULL) return opt;
1652 }
1653
1654 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1655 // Try to undo Phi of AddP:
1656 // (Phi (AddP base base y) (AddP base2 base2 y))
1657 // becomes:
1658 // newbase := (Phi base base2)
1659 // (AddP newbase newbase y)
1660 //
1661 // This occurs as a result of unsuccessful split_thru_phi and
1662 // interferes with taking advantage of addressing modes. See the
1663 // clone_shift_expressions code in matcher.cpp
1664 Node* addp = in(1);
1665 const Type* type = addp->in(AddPNode::Base)->bottom_type();
1666 Node* y = addp->in(AddPNode::Offset);
1667 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1668 // make sure that all the inputs are similar to the first one,
1669 // i.e. AddP with base == address and same offset as first AddP
1670 bool doit = true;
1671 for (uint i = 2; i < req(); i++) {
1672 if (in(i) == NULL ||
1673 in(i)->Opcode() != Op_AddP ||
1674 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1675 in(i)->in(AddPNode::Offset) != y) {
1676 doit = false;
1677 break;
1678 }
1679 // Accumulate type for resulting Phi
1680 type = type->meet(in(i)->in(AddPNode::Base)->bottom_type());
1681 }
1682 Node* base = NULL;
1683 if (doit) {
1684 // Check for neighboring AddP nodes in a tree.
1685 // If they have a base, use that it.
1686 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1687 Node* u = this->fast_out(k);
1688 if (u->is_AddP()) {
1689 Node* base2 = u->in(AddPNode::Base);
1690 if (base2 != NULL && !base2->is_top()) {
1691 if (base == NULL)
1692 base = base2;
1693 else if (base != base2)
1694 { doit = false; break; }
1695 }
1696 }
1697 }
1698 }
1699 if (doit) {
1700 if (base == NULL) {
1701 base = new (phase->C, in(0)->req()) PhiNode(in(0), type, NULL);
1702 for (uint i = 1; i < req(); i++) {
1703 base->init_req(i, in(i)->in(AddPNode::Base));
1704 }
1705 phase->is_IterGVN()->register_new_node_with_optimizer(base);
1706 }
1707 return new (phase->C, 4) AddPNode(base, base, y);
1708 }
1709 }
1710 }
1711
1712 // Split phis through memory merges, so that the memory merges will go away.
1713 // Piggy-back this transformation on the search for a unique input....
1714 // It will be as if the merged memory is the unique value of the phi.
1715 // (Do not attempt this optimization unless parsing is complete.
1716 // It would make the parser's memory-merge logic sick.)
1717 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1718 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1719 // see if this phi should be sliced
1720 uint merge_width = 0;
1721 bool saw_self = false;
1722 for( uint i=1; i<req(); ++i ) {// For all paths in
1723 Node *ii = in(i);
1724 if (ii->is_MergeMem()) {
1725 MergeMemNode* n = ii->as_MergeMem();
1726 merge_width = MAX2(merge_width, n->req());
1727 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1728 }
1729 }
1730
1731 // This restriction is temporarily necessary to ensure termination:
1732 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1733
1734 if (merge_width > Compile::AliasIdxRaw) {
1735 // found at least one non-empty MergeMem
1736 const TypePtr* at = adr_type();
1737 if (at != TypePtr::BOTTOM) {
1738 // Patch the existing phi to select an input from the merge:
1739 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1740 // Phi:AT1(...m1...)
1741 int alias_idx = phase->C->get_alias_index(at);
1742 for (uint i=1; i<req(); ++i) {
1743 Node *ii = in(i);
1744 if (ii->is_MergeMem()) {
1745 MergeMemNode* n = ii->as_MergeMem();
1746 // compress paths and change unreachable cycles to TOP
1747 // If not, we can update the input infinitely along a MergeMem cycle
1748 // Equivalent code is in MemNode::Ideal_common
1749 Node *m = phase->transform(n);
1750 if (outcnt() == 0) { // Above transform() may kill us!
1751 return top;
1752 }
1753 // If transformed to a MergeMem, get the desired slice
1754 // Otherwise the returned node represents memory for every slice
1755 Node *new_mem = (m->is_MergeMem()) ?
1756 m->as_MergeMem()->memory_at(alias_idx) : m;
1757 // Update input if it is progress over what we have now
1758 if (new_mem != ii) {
1759 set_req(i, new_mem);
1760 progress = this;
1761 }
1762 }
1763 }
1764 } else {
1765 // We know that at least one MergeMem->base_memory() == this
1766 // (saw_self == true). If all other inputs also references this phi
1767 // (directly or through data nodes) - it is dead loop.
1768 bool saw_safe_input = false;
1769 for (uint j = 1; j < req(); ++j) {
1770 Node *n = in(j);
1771 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1772 continue; // skip known cases
1773 if (!is_unsafe_data_reference(n)) {
1774 saw_safe_input = true; // found safe input
1775 break;
1776 }
1777 }
1778 if (!saw_safe_input)
1779 return top; // all inputs reference back to this phi - dead loop
1780
1781 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1782 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1783 PhaseIterGVN *igvn = phase->is_IterGVN();
1784 Node* hook = new (phase->C, 1) Node(1);
1785 PhiNode* new_base = (PhiNode*) clone();
1786 // Must eagerly register phis, since they participate in loops.
1787 if (igvn) {
1788 igvn->register_new_node_with_optimizer(new_base);
1789 hook->add_req(new_base);
1790 }
1791 MergeMemNode* result = MergeMemNode::make(phase->C, new_base);
1792 for (uint i = 1; i < req(); ++i) {
1793 Node *ii = in(i);
1794 if (ii->is_MergeMem()) {
1795 MergeMemNode* n = ii->as_MergeMem();
1796 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1797 // If we have not seen this slice yet, make a phi for it.
1798 bool made_new_phi = false;
1799 if (mms.is_empty()) {
1800 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1801 made_new_phi = true;
1802 if (igvn) {
1803 igvn->register_new_node_with_optimizer(new_phi);
1804 hook->add_req(new_phi);
1805 }
1806 mms.set_memory(new_phi);
1807 }
1808 Node* phi = mms.memory();
1809 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1810 phi->set_req(i, mms.memory2());
1811 }
1812 }
1813 }
1814 // Distribute all self-loops.
1815 { // (Extra braces to hide mms.)
1816 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1817 Node* phi = mms.memory();
1818 for (uint i = 1; i < req(); ++i) {
1819 if (phi->in(i) == this) phi->set_req(i, phi);
1820 }
1821 }
1822 }
1823 // now transform the new nodes, and return the mergemem
1824 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1825 Node* phi = mms.memory();
1826 mms.set_memory(phase->transform(phi));
1827 }
1828 if (igvn) { // Unhook.
1829 igvn->hash_delete(hook);
1830 for (uint i = 1; i < hook->req(); i++) {
1831 hook->set_req(i, NULL);
1832 }
1833 }
1834 // Replace self with the result.
1835 return result;
1836 }
1837 }
1838 //
1839 // Other optimizations on the memory chain
1840 //
1841 const TypePtr* at = adr_type();
1842 for( uint i=1; i<req(); ++i ) {// For all paths in
1843 Node *ii = in(i);
1844 Node *new_in = MemNode::optimize_memory_chain(ii, at, phase);
1845 if (ii != new_in ) {
1846 set_req(i, new_in);
1847 progress = this;
1848 }
1849 }
1850 }
1851
1852 #ifdef _LP64
1853 // Push DecodeN down through phi.
1854 // The rest of phi graph will transform by split EncodeP node though phis up.
1855 if (UseCompressedOops && can_reshape && progress == NULL) {
1856 bool may_push = true;
1857 bool has_decodeN = false;
1858 for (uint i=1; i<req(); ++i) {// For all paths in
1859 Node *ii = in(i);
1860 if (ii->is_DecodeN() && ii->bottom_type() == bottom_type()) {
1861 // Do optimization if a non dead path exist.
1862 if (ii->in(1)->bottom_type() != Type::TOP) {
1863 has_decodeN = true;
1864 }
1865 } else if (!ii->is_Phi()) {
1866 may_push = false;
1867 }
1868 }
1869
1870 if (has_decodeN && may_push) {
1871 PhaseIterGVN *igvn = phase->is_IterGVN();
1872 // Make narrow type for new phi.
1873 const Type* narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
1874 PhiNode* new_phi = new (phase->C, r->req()) PhiNode(r, narrow_t);
1875 uint orig_cnt = req();
1876 for (uint i=1; i<req(); ++i) {// For all paths in
1877 Node *ii = in(i);
1878 Node* new_ii = NULL;
1879 if (ii->is_DecodeN()) {
1880 assert(ii->bottom_type() == bottom_type(), "sanity");
1881 new_ii = ii->in(1);
1882 } else {
1883 assert(ii->is_Phi(), "sanity");
1884 if (ii->as_Phi() == this) {
1885 new_ii = new_phi;
1886 } else {
1887 new_ii = new (phase->C, 2) EncodePNode(ii, narrow_t);
1888 igvn->register_new_node_with_optimizer(new_ii);
1889 }
1890 }
1891 new_phi->set_req(i, new_ii);
1892 }
1893 igvn->register_new_node_with_optimizer(new_phi, this);
1894 progress = new (phase->C, 2) DecodeNNode(new_phi, bottom_type());
1895 }
1896 }
1897 #endif
1898
1899 return progress; // Return any progress
1900 }
1901
1902 //------------------------------is_tripcount-----------------------------------
1903 bool PhiNode::is_tripcount() const {
1904 return (in(0) != NULL && in(0)->is_CountedLoop() &&
1905 in(0)->as_CountedLoop()->phi() == this);
1906 }
1907
1908 //------------------------------out_RegMask------------------------------------
1909 const RegMask &PhiNode::in_RegMask(uint i) const {
1910 return i ? out_RegMask() : RegMask::Empty;
1911 }
1912
1913 const RegMask &PhiNode::out_RegMask() const {
1914 uint ideal_reg = Matcher::base2reg[_type->base()];
1915 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
1916 if( ideal_reg == 0 ) return RegMask::Empty;
1917 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
1918 }
1919
1920 #ifndef PRODUCT
1921 void PhiNode::dump_spec(outputStream *st) const {
1922 TypeNode::dump_spec(st);
1923 if (is_tripcount()) {
1924 st->print(" #tripcount");
1925 }
1926 }
1927 #endif
1928
1929
1930 //=============================================================================
1931 const Type *GotoNode::Value( PhaseTransform *phase ) const {
1932 // If the input is reachable, then we are executed.
1933 // If the input is not reachable, then we are not executed.
1934 return phase->type(in(0));
1935 }
1936
1937 Node *GotoNode::Identity( PhaseTransform *phase ) {
1938 return in(0); // Simple copy of incoming control
1939 }
1940
1941 const RegMask &GotoNode::out_RegMask() const {
1942 return RegMask::Empty;
1943 }
1944
1945 //=============================================================================
1946 const RegMask &JumpNode::out_RegMask() const {
1947 return RegMask::Empty;
1948 }
1949
1950 //=============================================================================
1951 const RegMask &JProjNode::out_RegMask() const {
1952 return RegMask::Empty;
1953 }
1954
1955 //=============================================================================
1956 const RegMask &CProjNode::out_RegMask() const {
1957 return RegMask::Empty;
1958 }
1959
1960
1961
1962 //=============================================================================
1963
1964 uint PCTableNode::hash() const { return Node::hash() + _size; }
1965 uint PCTableNode::cmp( const Node &n ) const
1966 { return _size == ((PCTableNode&)n)._size; }
1967
1968 const Type *PCTableNode::bottom_type() const {
1969 const Type** f = TypeTuple::fields(_size);
1970 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
1971 return TypeTuple::make(_size, f);
1972 }
1973
1974 //------------------------------Value------------------------------------------
1975 // Compute the type of the PCTableNode. If reachable it is a tuple of
1976 // Control, otherwise the table targets are not reachable
1977 const Type *PCTableNode::Value( PhaseTransform *phase ) const {
1978 if( phase->type(in(0)) == Type::CONTROL )
1979 return bottom_type();
1980 return Type::TOP; // All paths dead? Then so are we
1981 }
1982
1983 //------------------------------Ideal------------------------------------------
1984 // Return a node which is more "ideal" than the current node. Strip out
1985 // control copies
1986 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1987 return remove_dead_region(phase, can_reshape) ? this : NULL;
1988 }
1989
1990 //=============================================================================
1991 uint JumpProjNode::hash() const {
1992 return Node::hash() + _dest_bci;
1993 }
1994
1995 uint JumpProjNode::cmp( const Node &n ) const {
1996 return ProjNode::cmp(n) &&
1997 _dest_bci == ((JumpProjNode&)n)._dest_bci;
1998 }
1999
2000 #ifndef PRODUCT
2001 void JumpProjNode::dump_spec(outputStream *st) const {
2002 ProjNode::dump_spec(st);
2003 st->print("@bci %d ",_dest_bci);
2004 }
2005 #endif
2006
2007 //=============================================================================
2008 //------------------------------Value------------------------------------------
2009 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2010 // have the default "fall_through_index" path.
2011 const Type *CatchNode::Value( PhaseTransform *phase ) const {
2012 // Unreachable? Then so are all paths from here.
2013 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2014 // First assume all paths are reachable
2015 const Type** f = TypeTuple::fields(_size);
2016 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2017 // Identify cases that will always throw an exception
2018 // () rethrow call
2019 // () virtual or interface call with NULL receiver
2020 // () call is a check cast with incompatible arguments
2021 if( in(1)->is_Proj() ) {
2022 Node *i10 = in(1)->in(0);
2023 if( i10->is_Call() ) {
2024 CallNode *call = i10->as_Call();
2025 // Rethrows always throw exceptions, never return
2026 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2027 f[CatchProjNode::fall_through_index] = Type::TOP;
2028 } else if( call->req() > TypeFunc::Parms ) {
2029 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2030 // Check for null receiver to virtual or interface calls
2031 if( call->is_CallDynamicJava() &&
2032 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2033 f[CatchProjNode::fall_through_index] = Type::TOP;
2034 }
2035 } // End of if not a runtime stub
2036 } // End of if have call above me
2037 } // End of slot 1 is not a projection
2038 return TypeTuple::make(_size, f);
2039 }
2040
2041 //=============================================================================
2042 uint CatchProjNode::hash() const {
2043 return Node::hash() + _handler_bci;
2044 }
2045
2046
2047 uint CatchProjNode::cmp( const Node &n ) const {
2048 return ProjNode::cmp(n) &&
2049 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2050 }
2051
2052
2053 //------------------------------Identity---------------------------------------
2054 // If only 1 target is possible, choose it if it is the main control
2055 Node *CatchProjNode::Identity( PhaseTransform *phase ) {
2056 // If my value is control and no other value is, then treat as ID
2057 const TypeTuple *t = phase->type(in(0))->is_tuple();
2058 if (t->field_at(_con) != Type::CONTROL) return this;
2059 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2060 // also remove any exception table entry. Thus we must know the call
2061 // feeding the Catch will not really throw an exception. This is ok for
2062 // the main fall-thru control (happens when we know a call can never throw
2063 // an exception) or for "rethrow", because a further optimization will
2064 // yank the rethrow (happens when we inline a function that can throw an
2065 // exception and the caller has no handler). Not legal, e.g., for passing
2066 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2067 // These cases MUST throw an exception via the runtime system, so the VM
2068 // will be looking for a table entry.
2069 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2070 CallNode *call;
2071 if (_con != TypeFunc::Control && // Bail out if not the main control.
2072 !(proj->is_Proj() && // AND NOT a rethrow
2073 proj->in(0)->is_Call() &&
2074 (call = proj->in(0)->as_Call()) &&
2075 call->entry_point() == OptoRuntime::rethrow_stub()))
2076 return this;
2077
2078 // Search for any other path being control
2079 for (uint i = 0; i < t->cnt(); i++) {
2080 if (i != _con && t->field_at(i) == Type::CONTROL)
2081 return this;
2082 }
2083 // Only my path is possible; I am identity on control to the jump
2084 return in(0)->in(0);
2085 }
2086
2087
2088 #ifndef PRODUCT
2089 void CatchProjNode::dump_spec(outputStream *st) const {
2090 ProjNode::dump_spec(st);
2091 st->print("@bci %d ",_handler_bci);
2092 }
2093 #endif
2094
2095 //=============================================================================
2096 //------------------------------Identity---------------------------------------
2097 // Check for CreateEx being Identity.
2098 Node *CreateExNode::Identity( PhaseTransform *phase ) {
2099 if( phase->type(in(1)) == Type::TOP ) return in(1);
2100 if( phase->type(in(0)) == Type::TOP ) return in(0);
2101 // We only come from CatchProj, unless the CatchProj goes away.
2102 // If the CatchProj is optimized away, then we just carry the
2103 // exception oop through.
2104 CallNode *call = in(1)->in(0)->as_Call();
2105
2106 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2107 ? this
2108 : call->in(TypeFunc::Parms);
2109 }
2110
2111 //=============================================================================
2112 //------------------------------Value------------------------------------------
2113 // Check for being unreachable.
2114 const Type *NeverBranchNode::Value( PhaseTransform *phase ) const {
2115 if (!in(0) || in(0)->is_top()) return Type::TOP;
2116 return bottom_type();
2117 }
2118
2119 //------------------------------Ideal------------------------------------------
2120 // Check for no longer being part of a loop
2121 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2122 if (can_reshape && !in(0)->is_Loop()) {
2123 // Dead code elimination can sometimes delete this projection so
2124 // if it's not there, there's nothing to do.
2125 Node* fallthru = proj_out(0);
2126 if (fallthru != NULL) {
2127 phase->is_IterGVN()->replace_node(fallthru, in(0));
2128 }
2129 return phase->C->top();
2130 }
2131 return NULL;
2132 }
2133
2134 #ifndef PRODUCT
2135 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2136 st->print("%s", Name());
2137 }
2138 #endif