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