1 /*
2 * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Portions of code courtesy of Clifford Click
26
27 // Optimization - Graph Style
28
29 #include "incls/_precompiled.incl"
30 #include "incls/_cfgnode.cpp.incl"
31
32 //=============================================================================
33 //------------------------------Value------------------------------------------
34 // Compute the type of the RegionNode.
35 const Type *RegionNode::Value( PhaseTransform *phase ) const {
36 for( uint i=1; i<req(); ++i ) { // For all paths in
37 Node *n = in(i); // Get Control source
38 if( !n ) continue; // Missing inputs are TOP
39 if( phase->type(n) == Type::CONTROL )
40 return Type::CONTROL;
41 }
42 return Type::TOP; // All paths dead? Then so are we
43 }
44
45 //------------------------------Identity---------------------------------------
46 // Check for Region being Identity.
47 Node *RegionNode::Identity( PhaseTransform *phase ) {
48 // Cannot have Region be an identity, even if it has only 1 input.
49 // Phi users cannot have their Region input folded away for them,
50 // since they need to select the proper data input
51 return this;
52 }
53
54 //------------------------------merge_region-----------------------------------
55 // If a Region flows into a Region, merge into one big happy merge. This is
56 // hard to do if there is stuff that has to happen
57 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
58 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
59 return NULL;
60 Node *progress = NULL; // Progress flag
61 PhaseIterGVN *igvn = phase->is_IterGVN();
62
63 uint rreq = region->req();
64 for( uint i = 1; i < rreq; i++ ) {
65 Node *r = region->in(i);
66 if( r && r->Opcode() == Op_Region && // Found a region?
67 r->in(0) == r && // Not already collapsed?
68 r != region && // Avoid stupid situations
69 r->outcnt() == 2 ) { // Self user and 'region' user only?
70 assert(!r->as_Region()->has_phi(), "no phi users");
71 if( !progress ) { // No progress
72 if (region->has_phi()) {
73 return NULL; // Only flatten if no Phi users
74 // igvn->hash_delete( phi );
75 }
76 igvn->hash_delete( region );
77 progress = region; // Making progress
78 }
79 igvn->hash_delete( r );
80
81 // Append inputs to 'r' onto 'region'
82 for( uint j = 1; j < r->req(); j++ ) {
83 // Move an input from 'r' to 'region'
84 region->add_req(r->in(j));
85 r->set_req(j, phase->C->top());
86 // Update phis of 'region'
87 //for( uint k = 0; k < max; k++ ) {
88 // Node *phi = region->out(k);
89 // if( phi->is_Phi() ) {
90 // phi->add_req(phi->in(i));
91 // }
92 //}
93
94 rreq++; // One more input to Region
95 } // Found a region to merge into Region
96 // Clobber pointer to the now dead 'r'
97 region->set_req(i, phase->C->top());
98 }
99 }
100
101 return progress;
102 }
103
104
105
106 //--------------------------------has_phi--------------------------------------
107 // Helper function: Return any PhiNode that uses this region or NULL
108 PhiNode* RegionNode::has_phi() const {
109 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
110 Node* phi = fast_out(i);
111 if (phi->is_Phi()) { // Check for Phi users
112 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
113 return phi->as_Phi(); // this one is good enough
114 }
115 }
116
117 return NULL;
118 }
119
120
121 //-----------------------------has_unique_phi----------------------------------
122 // Helper function: Return the only PhiNode that uses this region or NULL
123 PhiNode* RegionNode::has_unique_phi() const {
124 // Check that only one use is a Phi
125 PhiNode* only_phi = NULL;
126 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
127 Node* phi = fast_out(i);
128 if (phi->is_Phi()) { // Check for Phi users
129 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
130 if (only_phi == NULL) {
131 only_phi = phi->as_Phi();
132 } else {
133 return NULL; // multiple phis
134 }
135 }
136 }
137
138 return only_phi;
139 }
140
141
142 //------------------------------check_phi_clipping-----------------------------
143 // Helper function for RegionNode's identification of FP clipping
144 // Check inputs to the Phi
145 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
146 min = NULL;
147 max = NULL;
148 val = NULL;
149 min_idx = 0;
150 max_idx = 0;
151 val_idx = 0;
152 uint phi_max = phi->req();
153 if( phi_max == 4 ) {
154 for( uint j = 1; j < phi_max; ++j ) {
155 Node *n = phi->in(j);
156 int opcode = n->Opcode();
157 switch( opcode ) {
158 case Op_ConI:
159 {
160 if( min == NULL ) {
161 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
162 min_idx = j;
163 } else {
164 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
165 max_idx = j;
166 if( min->get_int() > max->get_int() ) {
167 // Swap min and max
168 ConNode *temp;
169 uint temp_idx;
170 temp = min; min = max; max = temp;
171 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
172 }
173 }
174 }
175 break;
176 default:
177 {
178 val = n;
179 val_idx = j;
180 }
181 break;
182 }
183 }
184 }
185 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
186 }
187
188
189 //------------------------------check_if_clipping------------------------------
190 // Helper function for RegionNode's identification of FP clipping
191 // Check that inputs to Region come from two IfNodes,
192 //
193 // If
194 // False True
195 // If |
196 // False True |
197 // | | |
198 // RegionNode_inputs
199 //
200 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
201 top_if = NULL;
202 bot_if = NULL;
203
204 // Check control structure above RegionNode for (if ( if ) )
205 Node *in1 = region->in(1);
206 Node *in2 = region->in(2);
207 Node *in3 = region->in(3);
208 // Check that all inputs are projections
209 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
210 Node *in10 = in1->in(0);
211 Node *in20 = in2->in(0);
212 Node *in30 = in3->in(0);
213 // Check that #1 and #2 are ifTrue and ifFalse from same If
214 if( in10 != NULL && in10->is_If() &&
215 in20 != NULL && in20->is_If() &&
216 in30 != NULL && in30->is_If() && in10 == in20 &&
217 (in1->Opcode() != in2->Opcode()) ) {
218 Node *in100 = in10->in(0);
219 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
220 // Check that control for in10 comes from other branch of IF from in3
221 if( in1000 != NULL && in1000->is_If() &&
222 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
223 // Control pattern checks
224 top_if = (IfNode*)in1000;
225 bot_if = (IfNode*)in10;
226 }
227 }
228 }
229
230 return (top_if != NULL);
231 }
232
233
234 //------------------------------check_convf2i_clipping-------------------------
235 // Helper function for RegionNode's identification of FP clipping
236 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
237 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
238 convf2i = NULL;
239
240 // Check for the RShiftNode
241 Node *rshift = phi->in(idx);
242 assert( rshift, "Previous checks ensure phi input is present");
243 if( rshift->Opcode() != Op_RShiftI ) { return false; }
244
245 // Check for the LShiftNode
246 Node *lshift = rshift->in(1);
247 assert( lshift, "Previous checks ensure phi input is present");
248 if( lshift->Opcode() != Op_LShiftI ) { return false; }
249
250 // Check for the ConvF2INode
251 Node *conv = lshift->in(1);
252 if( conv->Opcode() != Op_ConvF2I ) { return false; }
253
254 // Check that shift amounts are only to get sign bits set after F2I
255 jint max_cutoff = max->get_int();
256 jint min_cutoff = min->get_int();
257 jint left_shift = lshift->in(2)->get_int();
258 jint right_shift = rshift->in(2)->get_int();
259 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
260 if( left_shift != right_shift ||
261 0 > left_shift || left_shift >= BitsPerJavaInteger ||
262 max_post_shift < max_cutoff ||
263 max_post_shift < -min_cutoff ) {
264 // Shifts are necessary but current transformation eliminates them
265 return false;
266 }
267
268 // OK to return the result of ConvF2I without shifting
269 convf2i = (ConvF2INode*)conv;
270 return true;
271 }
272
273
274 //------------------------------check_compare_clipping-------------------------
275 // Helper function for RegionNode's identification of FP clipping
276 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
277 Node *i1 = iff->in(1);
278 if ( !i1->is_Bool() ) { return false; }
279 BoolNode *bool1 = i1->as_Bool();
280 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
281 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
282 const Node *cmpF = bool1->in(1);
283 if( cmpF->Opcode() != Op_CmpF ) { return false; }
284 // Test that the float value being compared against
285 // is equivalent to the int value used as a limit
286 Node *nodef = cmpF->in(2);
287 if( nodef->Opcode() != Op_ConF ) { return false; }
288 jfloat conf = nodef->getf();
289 jint coni = limit->get_int();
290 if( ((int)conf) != coni ) { return false; }
291 input = cmpF->in(1);
292 return true;
293 }
294
295 //------------------------------is_unreachable_region--------------------------
296 // Find if the Region node is reachable from the root.
297 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
298 assert(req() == 2, "");
299
300 // First, cut the simple case of fallthrough region when NONE of
301 // region's phis references itself directly or through a data node.
302 uint max = outcnt();
303 uint i;
304 for (i = 0; i < max; i++) {
305 Node* phi = raw_out(i);
306 if (phi != NULL && phi->is_Phi()) {
307 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
308 if (phi->outcnt() == 0)
309 continue; // Safe case - no loops
310 if (phi->outcnt() == 1) {
311 Node* u = phi->raw_out(0);
312 // Skip if only one use is an other Phi or Call or Uncommon trap.
313 // It is safe to consider this case as fallthrough.
314 if (u != NULL && (u->is_Phi() || u->is_CFG()))
315 continue;
316 }
317 // Check when phi references itself directly or through an other node.
318 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
319 break; // Found possible unsafe data loop.
320 }
321 }
322 if (i >= max)
323 return false; // An unsafe case was NOT found - don't need graph walk.
324
325 // Unsafe case - check if the Region node is reachable from root.
326 ResourceMark rm;
327
328 Arena *a = Thread::current()->resource_area();
329 Node_List nstack(a);
330 VectorSet visited(a);
331
332 // Mark all control nodes reachable from root outputs
333 Node *n = (Node*)phase->C->root();
334 nstack.push(n);
335 visited.set(n->_idx);
336 while (nstack.size() != 0) {
337 n = nstack.pop();
338 uint max = n->outcnt();
339 for (uint i = 0; i < max; i++) {
340 Node* m = n->raw_out(i);
341 if (m != NULL && m->is_CFG()) {
342 if (phase->eqv(m, this)) {
343 return false; // We reached the Region node - it is not dead.
344 }
345 if (!visited.test_set(m->_idx))
346 nstack.push(m);
347 }
348 }
349 }
350
351 return true; // The Region node is unreachable - it is dead.
352 }
353
354 //------------------------------Ideal------------------------------------------
355 // Return a node which is more "ideal" than the current node. Must preserve
356 // the CFG, but we can still strip out dead paths.
357 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
358 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
359 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
360
361 // Check for RegionNode with no Phi users and both inputs come from either
362 // arm of the same IF. If found, then the control-flow split is useless.
363 bool has_phis = false;
364 if (can_reshape) { // Need DU info to check for Phi users
365 has_phis = (has_phi() != NULL); // Cache result
366 if (!has_phis) { // No Phi users? Nothing merging?
367 for (uint i = 1; i < req()-1; i++) {
368 Node *if1 = in(i);
369 if( !if1 ) continue;
370 Node *iff = if1->in(0);
371 if( !iff || !iff->is_If() ) continue;
372 for( uint j=i+1; j<req(); j++ ) {
373 if( in(j) && in(j)->in(0) == iff &&
374 if1->Opcode() != in(j)->Opcode() ) {
375 // Add the IF Projections to the worklist. They (and the IF itself)
376 // will be eliminated if dead.
377 phase->is_IterGVN()->add_users_to_worklist(iff);
378 set_req(i, iff->in(0));// Skip around the useless IF diamond
379 set_req(j, NULL);
380 return this; // Record progress
381 }
382 }
383 }
384 }
385 }
386
387 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
388 // degrades to a copy.
389 bool add_to_worklist = false;
390 int cnt = 0; // Count of values merging
391 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
392 int del_it = 0; // The last input path we delete
393 // For all inputs...
394 for( uint i=1; i<req(); ++i ){// For all paths in
395 Node *n = in(i); // Get the input
396 if( n != NULL ) {
397 // Remove useless control copy inputs
398 if( n->is_Region() && n->as_Region()->is_copy() ) {
399 set_req(i, n->nonnull_req());
400 i--;
401 continue;
402 }
403 if( n->is_Proj() ) { // Remove useless rethrows
404 Node *call = n->in(0);
405 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
406 set_req(i, call->in(0));
407 i--;
408 continue;
409 }
410 }
411 if( phase->type(n) == Type::TOP ) {
412 set_req(i, NULL); // Ignore TOP inputs
413 i--;
414 continue;
415 }
416 cnt++; // One more value merging
417
418 } else if (can_reshape) { // Else found dead path with DU info
419 PhaseIterGVN *igvn = phase->is_IterGVN();
420 del_req(i); // Yank path from self
421 del_it = i;
422 uint max = outcnt();
423 DUIterator j;
424 bool progress = true;
425 while(progress) { // Need to establish property over all users
426 progress = false;
427 for (j = outs(); has_out(j); j++) {
428 Node *n = out(j);
429 if( n->req() != req() && n->is_Phi() ) {
430 assert( n->in(0) == this, "" );
431 igvn->hash_delete(n); // Yank from hash before hacking edges
432 n->set_req_X(i,NULL,igvn);// Correct DU info
433 n->del_req(i); // Yank path from Phis
434 if( max != outcnt() ) {
435 progress = true;
436 j = refresh_out_pos(j);
437 max = outcnt();
438 }
439 }
440 }
441 }
442 add_to_worklist = true;
443 i--;
444 }
445 }
446
447 if (can_reshape && cnt == 1) {
448 // Is it dead loop?
449 // If it is LoopNopde it had 2 (+1 itself) inputs and
450 // one of them was cut. The loop is dead if it was EntryContol.
451 assert(!this->is_Loop() || cnt_orig == 3, "Loop node should have 3 inputs");
452 if (this->is_Loop() && del_it == LoopNode::EntryControl ||
453 !this->is_Loop() && has_phis && is_unreachable_region(phase)) {
454 // Yes, the region will be removed during the next step below.
455 // Cut the backedge input and remove phis since no data paths left.
456 // We don't cut outputs to other nodes here since we need to put them
457 // on the worklist.
458 del_req(1);
459 cnt = 0;
460 assert( req() == 1, "no more inputs expected" );
461 uint max = outcnt();
462 bool progress = true;
463 Node *top = phase->C->top();
464 PhaseIterGVN *igvn = phase->is_IterGVN();
465 DUIterator j;
466 while(progress) {
467 progress = false;
468 for (j = outs(); has_out(j); j++) {
469 Node *n = out(j);
470 if( n->is_Phi() ) {
471 assert( igvn->eqv(n->in(0), this), "" );
472 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
473 // Break dead loop data path.
474 // Eagerly replace phis with top to avoid phis copies generation.
475 igvn->add_users_to_worklist(n);
476 igvn->hash_delete(n); // Yank from hash before hacking edges
477 igvn->subsume_node(n, top);
478 if( max != outcnt() ) {
479 progress = true;
480 j = refresh_out_pos(j);
481 max = outcnt();
482 }
483 }
484 }
485 }
486 add_to_worklist = true;
487 }
488 }
489 if (add_to_worklist) {
490 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
491 }
492
493 if( cnt <= 1 ) { // Only 1 path in?
494 set_req(0, NULL); // Null control input for region copy
495 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
496 // No inputs or all inputs are NULL.
497 return NULL;
498 } else if (can_reshape) { // Optimization phase - remove the node
499 PhaseIterGVN *igvn = phase->is_IterGVN();
500 Node *parent_ctrl;
501 if( cnt == 0 ) {
502 assert( req() == 1, "no inputs expected" );
503 // During IGVN phase such region will be subsumed by TOP node
504 // so region's phis will have TOP as control node.
505 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
506 // Also set other user's input to top.
507 parent_ctrl = phase->C->top();
508 } else {
509 // The fallthrough case since we already checked dead loops above.
510 parent_ctrl = in(1);
511 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
512 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
513 }
514 if (!add_to_worklist)
515 igvn->add_users_to_worklist(this); // Check for further allowed opts
516 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
517 Node* n = last_out(i);
518 igvn->hash_delete(n); // Remove from worklist before modifying edges
519 if( n->is_Phi() ) { // Collapse all Phis
520 // Eagerly replace phis to avoid copies generation.
521 igvn->add_users_to_worklist(n);
522 igvn->hash_delete(n); // Yank from hash before hacking edges
523 if( cnt == 0 ) {
524 assert( n->req() == 1, "No data inputs expected" );
525 igvn->subsume_node(n, parent_ctrl); // replaced by top
526 } else {
527 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
528 Node* in1 = n->in(1); // replaced by unique input
529 if( n->as_Phi()->is_unsafe_data_reference(in1) )
530 in1 = phase->C->top(); // replaced by top
531 igvn->subsume_node(n, in1);
532 }
533 }
534 else if( n->is_Region() ) { // Update all incoming edges
535 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
536 uint uses_found = 0;
537 for( uint k=1; k < n->req(); k++ ) {
538 if( n->in(k) == this ) {
539 n->set_req(k, parent_ctrl);
540 uses_found++;
541 }
542 }
543 if( uses_found > 1 ) { // (--i) done at the end of the loop.
544 i -= (uses_found - 1);
545 }
546 }
547 else {
548 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
549 n->set_req(0, parent_ctrl);
550 }
551 #ifdef ASSERT
552 for( uint k=0; k < n->req(); k++ ) {
553 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
554 }
555 #endif
556 }
557 // Remove the RegionNode itself from DefUse info
558 igvn->remove_dead_node(this);
559 return NULL;
560 }
561 return this; // Record progress
562 }
563
564
565 // If a Region flows into a Region, merge into one big happy merge.
566 if (can_reshape) {
567 Node *m = merge_region(this, phase);
568 if (m != NULL) return m;
569 }
570
571 // Check if this region is the root of a clipping idiom on floats
572 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
573 // Check that only one use is a Phi and that it simplifies to two constants +
574 PhiNode* phi = has_unique_phi();
575 if (phi != NULL) { // One Phi user
576 // Check inputs to the Phi
577 ConNode *min;
578 ConNode *max;
579 Node *val;
580 uint min_idx;
581 uint max_idx;
582 uint val_idx;
583 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
584 IfNode *top_if;
585 IfNode *bot_if;
586 if( check_if_clipping( this, bot_if, top_if ) ) {
587 // Control pattern checks, now verify compares
588 Node *top_in = NULL; // value being compared against
589 Node *bot_in = NULL;
590 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
591 check_compare_clipping( false, top_if, max, top_in ) ) {
592 if( bot_in == top_in ) {
593 PhaseIterGVN *gvn = phase->is_IterGVN();
594 assert( gvn != NULL, "Only had DefUse info in IterGVN");
595 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
596
597 // Check for the ConvF2INode
598 ConvF2INode *convf2i;
599 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
600 convf2i->in(1) == bot_in ) {
601 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
602 // max test
603 Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, min ));
604 Node *boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::lt ));
605 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
606 Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
607 Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
608 // min test
609 cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, max ));
610 boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::gt ));
611 iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
612 Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
613 ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
614 // update input edges to region node
615 set_req_X( min_idx, if_min, gvn );
616 set_req_X( max_idx, if_max, gvn );
617 set_req_X( val_idx, ifF, gvn );
618 // remove unnecessary 'LShiftI; RShiftI' idiom
619 gvn->hash_delete(phi);
620 phi->set_req_X( val_idx, convf2i, gvn );
621 gvn->hash_find_insert(phi);
622 // Return transformed region node
623 return this;
624 }
625 }
626 }
627 }
628 }
629 }
630 }
631
632 return NULL;
633 }
634
635
636
637 const RegMask &RegionNode::out_RegMask() const {
638 return RegMask::Empty;
639 }
640
641 // Find the one non-null required input. RegionNode only
642 Node *Node::nonnull_req() const {
643 assert( is_Region(), "" );
644 for( uint i = 1; i < _cnt; i++ )
645 if( in(i) )
646 return in(i);
647 ShouldNotReachHere();
648 return NULL;
649 }
650
651
652 //=============================================================================
653 // note that these functions assume that the _adr_type field is flattened
654 uint PhiNode::hash() const {
655 const Type* at = _adr_type;
656 return TypeNode::hash() + (at ? at->hash() : 0);
657 }
658 uint PhiNode::cmp( const Node &n ) const {
659 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
660 }
661 static inline
662 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
663 if (at == NULL || at == TypePtr::BOTTOM) return at;
664 return Compile::current()->alias_type(at)->adr_type();
665 }
666
667 //----------------------------make---------------------------------------------
668 // create a new phi with edges matching r and set (initially) to x
669 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
670 uint preds = r->req(); // Number of predecessor paths
671 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
672 PhiNode* p = new (Compile::current(), preds) PhiNode(r, t, at);
673 for (uint j = 1; j < preds; j++) {
674 // Fill in all inputs, except those which the region does not yet have
675 if (r->in(j) != NULL)
676 p->init_req(j, x);
677 }
678 return p;
679 }
680 PhiNode* PhiNode::make(Node* r, Node* x) {
681 const Type* t = x->bottom_type();
682 const TypePtr* at = NULL;
683 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
684 return make(r, x, t, at);
685 }
686 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
687 const Type* t = x->bottom_type();
688 const TypePtr* at = NULL;
689 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
690 return new (Compile::current(), r->req()) PhiNode(r, t, at);
691 }
692
693
694 //------------------------slice_memory-----------------------------------------
695 // create a new phi with narrowed memory type
696 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
697 PhiNode* mem = (PhiNode*) clone();
698 *(const TypePtr**)&mem->_adr_type = adr_type;
699 // convert self-loops, or else we get a bad graph
700 for (uint i = 1; i < req(); i++) {
701 if ((const Node*)in(i) == this) mem->set_req(i, mem);
702 }
703 mem->verify_adr_type();
704 return mem;
705 }
706
707 //------------------------split_out_instance-----------------------------------
708 // Split out an instance type from a bottom phi.
709 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
710 assert(type() == Type::MEMORY && (adr_type() == TypePtr::BOTTOM ||
711 adr_type() == TypeRawPtr::BOTTOM) , "bottom or raw memory required");
712
713 // Check if an appropriate node already exists.
714 Node *region = in(0);
715 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
716 Node* use = region->fast_out(k);
717 if( use->is_Phi()) {
718 PhiNode *phi2 = use->as_Phi();
719 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
720 return phi2;
721 }
722 }
723 }
724 Compile *C = igvn->C;
725 Arena *a = Thread::current()->resource_area();
726 Node_Array node_map = new Node_Array(a);
727 Node_Stack stack(a, C->unique() >> 4);
728 PhiNode *nphi = slice_memory(at);
729 igvn->register_new_node_with_optimizer( nphi );
730 node_map.map(_idx, nphi);
731 stack.push((Node *)this, 1);
732 while(!stack.is_empty()) {
733 PhiNode *ophi = stack.node()->as_Phi();
734 uint i = stack.index();
735 assert(i >= 1, "not control edge");
736 stack.pop();
737 nphi = node_map[ophi->_idx]->as_Phi();
738 for (; i < ophi->req(); i++) {
739 Node *in = ophi->in(i);
740 if (in == NULL || igvn->type(in) == Type::TOP)
741 continue;
742 Node *opt = MemNode::optimize_simple_memory_chain(in, at, igvn);
743 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
744 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
745 opt = node_map[optphi->_idx];
746 if (opt == NULL) {
747 stack.push(ophi, i);
748 nphi = optphi->slice_memory(at);
749 igvn->register_new_node_with_optimizer( nphi );
750 node_map.map(optphi->_idx, nphi);
751 ophi = optphi;
752 i = 0; // will get incremented at top of loop
753 continue;
754 }
755 }
756 nphi->set_req(i, opt);
757 }
758 }
759 return nphi;
760 }
761
762 //------------------------verify_adr_type--------------------------------------
763 #ifdef ASSERT
764 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
765 if (visited.test_set(_idx)) return; //already visited
766
767 // recheck constructor invariants:
768 verify_adr_type(false);
769
770 // recheck local phi/phi consistency:
771 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
772 "adr_type must be consistent across phi nest");
773
774 // walk around
775 for (uint i = 1; i < req(); i++) {
776 Node* n = in(i);
777 if (n == NULL) continue;
778 const Node* np = in(i);
779 if (np->is_Phi()) {
780 np->as_Phi()->verify_adr_type(visited, at);
781 } else if (n->bottom_type() == Type::TOP
782 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
783 // ignore top inputs
784 } else {
785 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
786 // recheck phi/non-phi consistency at leaves:
787 assert((nat != NULL) == (at != NULL), "");
788 assert(nat == at || nat == TypePtr::BOTTOM,
789 "adr_type must be consistent at leaves of phi nest");
790 }
791 }
792 }
793
794 // Verify a whole nest of phis rooted at this one.
795 void PhiNode::verify_adr_type(bool recursive) const {
796 if (is_error_reported()) return; // muzzle asserts when debugging an error
797 if (Node::in_dump()) return; // muzzle asserts when printing
798
799 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
800
801 if (!VerifyAliases) return; // verify thoroughly only if requested
802
803 assert(_adr_type == flatten_phi_adr_type(_adr_type),
804 "Phi::adr_type must be pre-normalized");
805
806 if (recursive) {
807 VectorSet visited(Thread::current()->resource_area());
808 verify_adr_type(visited, _adr_type);
809 }
810 }
811 #endif
812
813
814 //------------------------------Value------------------------------------------
815 // Compute the type of the PhiNode
816 const Type *PhiNode::Value( PhaseTransform *phase ) const {
817 Node *r = in(0); // RegionNode
818 if( !r ) // Copy or dead
819 return in(1) ? phase->type(in(1)) : Type::TOP;
820
821 // Note: During parsing, phis are often transformed before their regions.
822 // This means we have to use type_or_null to defend against untyped regions.
823 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
824 return Type::TOP;
825
826 // Check for trip-counted loop. If so, be smarter.
827 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
828 if( l && l->can_be_counted_loop(phase) &&
829 ((const Node*)l->phi() == this) ) { // Trip counted loop!
830 // protect against init_trip() or limit() returning NULL
831 const Node *init = l->init_trip();
832 const Node *limit = l->limit();
833 if( init != NULL && limit != NULL && l->stride_is_con() ) {
834 const TypeInt *lo = init ->bottom_type()->isa_int();
835 const TypeInt *hi = limit->bottom_type()->isa_int();
836 if( lo && hi ) { // Dying loops might have TOP here
837 int stride = l->stride_con();
838 if( stride < 0 ) { // Down-counter loop
839 const TypeInt *tmp = lo; lo = hi; hi = tmp;
840 stride = -stride;
841 }
842 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
843 return TypeInt::make(lo->_lo,hi->_hi,3);
844 }
845 }
846 }
847
848 // Until we have harmony between classes and interfaces in the type
849 // lattice, we must tread carefully around phis which implicitly
850 // convert the one to the other.
851 const TypeInstPtr* ttip = _type->isa_instptr();
852 bool is_intf = false;
853 if (ttip != NULL) {
854 ciKlass* k = ttip->klass();
855 if (k->is_loaded() && k->is_interface())
856 is_intf = true;
857 }
858
859 // Default case: merge all inputs
860 const Type *t = Type::TOP; // Merged type starting value
861 for (uint i = 1; i < req(); ++i) {// For all paths in
862 // Reachable control path?
863 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
864 const Type* ti = phase->type(in(i));
865 // We assume that each input of an interface-valued Phi is a true
866 // subtype of that interface. This might not be true of the meet
867 // of all the input types. The lattice is not distributive in
868 // such cases. Ward off asserts in type.cpp by refusing to do
869 // meets between interfaces and proper classes.
870 const TypeInstPtr* tiip = ti->isa_instptr();
871 if (tiip) {
872 bool ti_is_intf = false;
873 ciKlass* k = tiip->klass();
874 if (k->is_loaded() && k->is_interface())
875 ti_is_intf = true;
876 if (is_intf != ti_is_intf)
877 { t = _type; break; }
878 }
879 t = t->meet(ti);
880 }
881 }
882
883 // The worst-case type (from ciTypeFlow) should be consistent with "t".
884 // That is, we expect that "t->higher_equal(_type)" holds true.
885 // There are various exceptions:
886 // - Inputs which are phis might in fact be widened unnecessarily.
887 // For example, an input might be a widened int while the phi is a short.
888 // - Inputs might be BotPtrs but this phi is dependent on a null check,
889 // and postCCP has removed the cast which encodes the result of the check.
890 // - The type of this phi is an interface, and the inputs are classes.
891 // - Value calls on inputs might produce fuzzy results.
892 // (Occurrences of this case suggest improvements to Value methods.)
893 //
894 // It is not possible to see Type::BOTTOM values as phi inputs,
895 // because the ciTypeFlow pre-pass produces verifier-quality types.
896 const Type* ft = t->filter(_type); // Worst case type
897
898 #ifdef ASSERT
899 // The following logic has been moved into TypeOopPtr::filter.
900 const Type* jt = t->join(_type);
901 if( jt->empty() ) { // Emptied out???
902
903 // Check for evil case of 't' being a class and '_type' expecting an
904 // interface. This can happen because the bytecodes do not contain
905 // enough type info to distinguish a Java-level interface variable
906 // from a Java-level object variable. If we meet 2 classes which
907 // both implement interface I, but their meet is at 'j/l/O' which
908 // doesn't implement I, we have no way to tell if the result should
909 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
910 // into a Phi which "knows" it's an Interface type we'll have to
911 // uplift the type.
912 if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() )
913 { assert(ft == _type, ""); } // Uplift to interface
914 // Otherwise it's something stupid like non-overlapping int ranges
915 // found on dying counted loops.
916 else
917 { assert(ft == Type::TOP, ""); } // Canonical empty value
918 }
919
920 else {
921
922 // If we have an interface-typed Phi and we narrow to a class type, the join
923 // should report back the class. However, if we have a J/L/Object
924 // class-typed Phi and an interface flows in, it's possible that the meet &
925 // join report an interface back out. This isn't possible but happens
926 // because the type system doesn't interact well with interfaces.
927 const TypeInstPtr *jtip = jt->isa_instptr();
928 if( jtip && ttip ) {
929 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
930 ttip->is_loaded() && !ttip->klass()->is_interface() )
931 // Happens in a CTW of rt.jar, 320-341, no extra flags
932 { assert(ft == ttip->cast_to_ptr_type(jtip->ptr()), ""); jt = ft; }
933 }
934 if (jt != ft && jt->base() == ft->base()) {
935 if (jt->isa_int() &&
936 jt->is_int()->_lo == ft->is_int()->_lo &&
937 jt->is_int()->_hi == ft->is_int()->_hi)
938 jt = ft;
939 if (jt->isa_long() &&
940 jt->is_long()->_lo == ft->is_long()->_lo &&
941 jt->is_long()->_hi == ft->is_long()->_hi)
942 jt = ft;
943 }
944 if (jt != ft) {
945 tty->print("merge type: "); t->dump(); tty->cr();
946 tty->print("kill type: "); _type->dump(); tty->cr();
947 tty->print("join type: "); jt->dump(); tty->cr();
948 tty->print("filter type: "); ft->dump(); tty->cr();
949 }
950 assert(jt == ft, "");
951 }
952 #endif //ASSERT
953
954 // Deal with conversion problems found in data loops.
955 ft = phase->saturate(ft, phase->type_or_null(this), _type);
956
957 return ft;
958 }
959
960
961 //------------------------------is_diamond_phi---------------------------------
962 // Does this Phi represent a simple well-shaped diamond merge? Return the
963 // index of the true path or 0 otherwise.
964 int PhiNode::is_diamond_phi() const {
965 // Check for a 2-path merge
966 Node *region = in(0);
967 if( !region ) return 0;
968 if( region->req() != 3 ) return 0;
969 if( req() != 3 ) return 0;
970 // Check that both paths come from the same If
971 Node *ifp1 = region->in(1);
972 Node *ifp2 = region->in(2);
973 if( !ifp1 || !ifp2 ) return 0;
974 Node *iff = ifp1->in(0);
975 if( !iff || !iff->is_If() ) return 0;
976 if( iff != ifp2->in(0) ) return 0;
977 // Check for a proper bool/cmp
978 const Node *b = iff->in(1);
979 if( !b->is_Bool() ) return 0;
980 const Node *cmp = b->in(1);
981 if( !cmp->is_Cmp() ) return 0;
982
983 // Check for branching opposite expected
984 if( ifp2->Opcode() == Op_IfTrue ) {
985 assert( ifp1->Opcode() == Op_IfFalse, "" );
986 return 2;
987 } else {
988 assert( ifp1->Opcode() == Op_IfTrue, "" );
989 return 1;
990 }
991 }
992
993 //----------------------------check_cmove_id-----------------------------------
994 // Check for CMove'ing a constant after comparing against the constant.
995 // Happens all the time now, since if we compare equality vs a constant in
996 // the parser, we "know" the variable is constant on one path and we force
997 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
998 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
999 // general in that we don't need constants. Since CMove's are only inserted
1000 // in very special circumstances, we do it here on generic Phi's.
1001 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1002 assert(true_path !=0, "only diamond shape graph expected");
1003
1004 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1005 // phi->region->if_proj->ifnode->bool->cmp
1006 Node* region = in(0);
1007 Node* iff = region->in(1)->in(0);
1008 BoolNode* b = iff->in(1)->as_Bool();
1009 Node* cmp = b->in(1);
1010 Node* tval = in(true_path);
1011 Node* fval = in(3-true_path);
1012 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1013 if (id == NULL)
1014 return NULL;
1015
1016 // Either value might be a cast that depends on a branch of 'iff'.
1017 // Since the 'id' value will float free of the diamond, either
1018 // decast or return failure.
1019 Node* ctl = id->in(0);
1020 if (ctl != NULL && ctl->in(0) == iff) {
1021 if (id->is_ConstraintCast()) {
1022 return id->in(1);
1023 } else {
1024 // Don't know how to disentangle this value.
1025 return NULL;
1026 }
1027 }
1028
1029 return id;
1030 }
1031
1032 //------------------------------Identity---------------------------------------
1033 // Check for Region being Identity.
1034 Node *PhiNode::Identity( PhaseTransform *phase ) {
1035 // Check for no merging going on
1036 // (There used to be special-case code here when this->region->is_Loop.
1037 // It would check for a tributary phi on the backedge that the main phi
1038 // trivially, perhaps with a single cast. The unique_input method
1039 // does all this and more, by reducing such tributaries to 'this'.)
1040 Node* uin = unique_input(phase);
1041 if (uin != NULL) {
1042 return uin;
1043 }
1044
1045 int true_path = is_diamond_phi();
1046 if (true_path != 0) {
1047 Node* id = is_cmove_id(phase, true_path);
1048 if (id != NULL) return id;
1049 }
1050
1051 return this; // No identity
1052 }
1053
1054 //-----------------------------unique_input------------------------------------
1055 // Find the unique value, discounting top, self-loops, and casts.
1056 // Return top if there are no inputs, and self if there are multiple.
1057 Node* PhiNode::unique_input(PhaseTransform* phase) {
1058 // 1) One unique direct input, or
1059 // 2) some of the inputs have an intervening ConstraintCast and
1060 // the type of input is the same or sharper (more specific)
1061 // than the phi's type.
1062 // 3) an input is a self loop
1063 //
1064 // 1) input or 2) input or 3) input __
1065 // / \ / \ \ / \
1066 // \ / | cast phi cast
1067 // phi \ / / \ /
1068 // phi / --
1069
1070 Node* r = in(0); // RegionNode
1071 if (r == NULL) return in(1); // Already degraded to a Copy
1072 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
1073 Node* direct_input = NULL; // The unique direct input
1074
1075 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1076 Node* rc = r->in(i);
1077 if (rc == NULL || phase->type(rc) == Type::TOP)
1078 continue; // ignore unreachable control path
1079 Node* n = in(i);
1080 Node* un = n->uncast();
1081 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1082 continue; // ignore if top, or in(i) and "this" are in a data cycle
1083 }
1084 // Check for a unique uncasted input
1085 if (uncasted_input == NULL) {
1086 uncasted_input = un;
1087 } else if (uncasted_input != un) {
1088 uncasted_input = NodeSentinel; // no unique uncasted input
1089 }
1090 // Check for a unique direct input
1091 if (direct_input == NULL) {
1092 direct_input = n;
1093 } else if (direct_input != n) {
1094 direct_input = NodeSentinel; // no unique direct input
1095 }
1096 }
1097 if (direct_input == NULL) {
1098 return phase->C->top(); // no inputs
1099 }
1100 assert(uncasted_input != NULL,"");
1101
1102 if (direct_input != NodeSentinel) {
1103 return direct_input; // one unique direct input
1104 }
1105 if (uncasted_input != NodeSentinel &&
1106 phase->type(uncasted_input)->higher_equal(type())) {
1107 return uncasted_input; // one unique uncasted input
1108 }
1109
1110 // Nothing.
1111 return NULL;
1112 }
1113
1114 //------------------------------is_x2logic-------------------------------------
1115 // Check for simple convert-to-boolean pattern
1116 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1117 // Convert Phi to an ConvIB.
1118 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1119 assert(true_path !=0, "only diamond shape graph expected");
1120 // Convert the true/false index into an expected 0/1 return.
1121 // Map 2->0 and 1->1.
1122 int flipped = 2-true_path;
1123
1124 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1125 // phi->region->if_proj->ifnode->bool->cmp
1126 Node *region = phi->in(0);
1127 Node *iff = region->in(1)->in(0);
1128 BoolNode *b = (BoolNode*)iff->in(1);
1129 const CmpNode *cmp = (CmpNode*)b->in(1);
1130
1131 Node *zero = phi->in(1);
1132 Node *one = phi->in(2);
1133 const Type *tzero = phase->type( zero );
1134 const Type *tone = phase->type( one );
1135
1136 // Check for compare vs 0
1137 const Type *tcmp = phase->type(cmp->in(2));
1138 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1139 // Allow cmp-vs-1 if the other input is bounded by 0-1
1140 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1141 return NULL;
1142 flipped = 1-flipped; // Test is vs 1 instead of 0!
1143 }
1144
1145 // Check for setting zero/one opposite expected
1146 if( tzero == TypeInt::ZERO ) {
1147 if( tone == TypeInt::ONE ) {
1148 } else return NULL;
1149 } else if( tzero == TypeInt::ONE ) {
1150 if( tone == TypeInt::ZERO ) {
1151 flipped = 1-flipped;
1152 } else return NULL;
1153 } else return NULL;
1154
1155 // Check for boolean test backwards
1156 if( b->_test._test == BoolTest::ne ) {
1157 } else if( b->_test._test == BoolTest::eq ) {
1158 flipped = 1-flipped;
1159 } else return NULL;
1160
1161 // Build int->bool conversion
1162 Node *n = new (phase->C, 2) Conv2BNode( cmp->in(1) );
1163 if( flipped )
1164 n = new (phase->C, 3) XorINode( phase->transform(n), phase->intcon(1) );
1165
1166 return n;
1167 }
1168
1169 //------------------------------is_cond_add------------------------------------
1170 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1171 // To be profitable the control flow has to disappear; there can be no other
1172 // values merging here. We replace the test-and-branch with:
1173 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1174 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1175 // Then convert Y to 0-or-Y and finally add.
1176 // This is a key transform for SpecJava _201_compress.
1177 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1178 assert(true_path !=0, "only diamond shape graph expected");
1179
1180 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1181 // phi->region->if_proj->ifnode->bool->cmp
1182 RegionNode *region = (RegionNode*)phi->in(0);
1183 Node *iff = region->in(1)->in(0);
1184 BoolNode* b = iff->in(1)->as_Bool();
1185 const CmpNode *cmp = (CmpNode*)b->in(1);
1186
1187 // Make sure only merging this one phi here
1188 if (region->has_unique_phi() != phi) return NULL;
1189
1190 // Make sure each arm of the diamond has exactly one output, which we assume
1191 // is the region. Otherwise, the control flow won't disappear.
1192 if (region->in(1)->outcnt() != 1) return NULL;
1193 if (region->in(2)->outcnt() != 1) return NULL;
1194
1195 // Check for "(P < Q)" of type signed int
1196 if (b->_test._test != BoolTest::lt) return NULL;
1197 if (cmp->Opcode() != Op_CmpI) return NULL;
1198
1199 Node *p = cmp->in(1);
1200 Node *q = cmp->in(2);
1201 Node *n1 = phi->in( true_path);
1202 Node *n2 = phi->in(3-true_path);
1203
1204 int op = n1->Opcode();
1205 if( op != Op_AddI // Need zero as additive identity
1206 /*&&op != Op_SubI &&
1207 op != Op_AddP &&
1208 op != Op_XorI &&
1209 op != Op_OrI*/ )
1210 return NULL;
1211
1212 Node *x = n2;
1213 Node *y = n1->in(1);
1214 if( n2 == n1->in(1) ) {
1215 y = n1->in(2);
1216 } else if( n2 == n1->in(1) ) {
1217 } else return NULL;
1218
1219 // Not so profitable if compare and add are constants
1220 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1221 return NULL;
1222
1223 Node *cmplt = phase->transform( new (phase->C, 3) CmpLTMaskNode(p,q) );
1224 Node *j_and = phase->transform( new (phase->C, 3) AndINode(cmplt,y) );
1225 return new (phase->C, 3) AddINode(j_and,x);
1226 }
1227
1228 //------------------------------is_absolute------------------------------------
1229 // Check for absolute value.
1230 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1231 assert(true_path !=0, "only diamond shape graph expected");
1232
1233 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1234 int phi_x_idx = 0; // Index of phi input where to find naked x
1235
1236 // ABS ends with the merge of 2 control flow paths.
1237 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1238 int false_path = 3 - true_path;
1239
1240 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1241 // phi->region->if_proj->ifnode->bool->cmp
1242 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1243
1244 // Check bool sense
1245 switch( bol->_test._test ) {
1246 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1247 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1248 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1249 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1250 default: return NULL; break;
1251 }
1252
1253 // Test is next
1254 Node *cmp = bol->in(1);
1255 const Type *tzero = NULL;
1256 switch( cmp->Opcode() ) {
1257 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1258 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1259 default: return NULL;
1260 }
1261
1262 // Find zero input of compare; the other input is being abs'd
1263 Node *x = NULL;
1264 bool flip = false;
1265 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1266 x = cmp->in(3 - cmp_zero_idx);
1267 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1268 // The test is inverted, we should invert the result...
1269 x = cmp->in(cmp_zero_idx);
1270 flip = true;
1271 } else {
1272 return NULL;
1273 }
1274
1275 // Next get the 2 pieces being selected, one is the original value
1276 // and the other is the negated value.
1277 if( phi_root->in(phi_x_idx) != x ) return NULL;
1278
1279 // Check other phi input for subtract node
1280 Node *sub = phi_root->in(3 - phi_x_idx);
1281
1282 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1283 if( tzero == TypeF::ZERO ) {
1284 if( sub->Opcode() != Op_SubF ||
1285 sub->in(2) != x ||
1286 phase->type(sub->in(1)) != tzero ) return NULL;
1287 x = new (phase->C, 2) AbsFNode(x);
1288 if (flip) {
1289 x = new (phase->C, 3) SubFNode(sub->in(1), phase->transform(x));
1290 }
1291 } else {
1292 if( sub->Opcode() != Op_SubD ||
1293 sub->in(2) != x ||
1294 phase->type(sub->in(1)) != tzero ) return NULL;
1295 x = new (phase->C, 2) AbsDNode(x);
1296 if (flip) {
1297 x = new (phase->C, 3) SubDNode(sub->in(1), phase->transform(x));
1298 }
1299 }
1300
1301 return x;
1302 }
1303
1304 //------------------------------split_once-------------------------------------
1305 // Helper for split_flow_path
1306 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1307 igvn->hash_delete(n); // Remove from hash before hacking edges
1308
1309 uint j = 1;
1310 for( uint i = phi->req()-1; i > 0; i-- ) {
1311 if( phi->in(i) == val ) { // Found a path with val?
1312 // Add to NEW Region/Phi, no DU info
1313 newn->set_req( j++, n->in(i) );
1314 // Remove from OLD Region/Phi
1315 n->del_req(i);
1316 }
1317 }
1318
1319 // Register the new node but do not transform it. Cannot transform until the
1320 // entire Region/Phi conglerate has been hacked as a single huge transform.
1321 igvn->register_new_node_with_optimizer( newn );
1322 // Now I can point to the new node.
1323 n->add_req(newn);
1324 igvn->_worklist.push(n);
1325 }
1326
1327 //------------------------------split_flow_path--------------------------------
1328 // Check for merging identical values and split flow paths
1329 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1330 BasicType bt = phi->type()->basic_type();
1331 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1332 return NULL; // Bail out on funny non-value stuff
1333 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1334 return NULL; // third unequal input to be worth doing
1335
1336 // Scan for a constant
1337 uint i;
1338 for( i = 1; i < phi->req()-1; i++ ) {
1339 Node *n = phi->in(i);
1340 if( !n ) return NULL;
1341 if( phase->type(n) == Type::TOP ) return NULL;
1342 if( n->Opcode() == Op_ConP )
1343 break;
1344 }
1345 if( i >= phi->req() ) // Only split for constants
1346 return NULL;
1347
1348 Node *val = phi->in(i); // Constant to split for
1349 uint hit = 0; // Number of times it occurs
1350
1351 for( ; i < phi->req(); i++ ){ // Count occurances of constant
1352 Node *n = phi->in(i);
1353 if( !n ) return NULL;
1354 if( phase->type(n) == Type::TOP ) return NULL;
1355 if( phi->in(i) == val )
1356 hit++;
1357 }
1358
1359 if( hit <= 1 || // Make sure we find 2 or more
1360 hit == phi->req()-1 ) // and not ALL the same value
1361 return NULL;
1362
1363 // Now start splitting out the flow paths that merge the same value.
1364 // Split first the RegionNode.
1365 PhaseIterGVN *igvn = phase->is_IterGVN();
1366 Node *r = phi->region();
1367 RegionNode *newr = new (phase->C, hit+1) RegionNode(hit+1);
1368 split_once(igvn, phi, val, r, newr);
1369
1370 // Now split all other Phis than this one
1371 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1372 Node* phi2 = r->fast_out(k);
1373 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1374 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1375 split_once(igvn, phi, val, phi2, newphi);
1376 }
1377 }
1378
1379 // Clean up this guy
1380 igvn->hash_delete(phi);
1381 for( i = phi->req()-1; i > 0; i-- ) {
1382 if( phi->in(i) == val ) {
1383 phi->del_req(i);
1384 }
1385 }
1386 phi->add_req(val);
1387
1388 return phi;
1389 }
1390
1391 //=============================================================================
1392 //------------------------------simple_data_loop_check-------------------------
1393 // Try to determing if the phi node in a simple safe/unsafe data loop.
1394 // Returns:
1395 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1396 // Safe - safe case when the phi and it's inputs reference only safe data
1397 // nodes;
1398 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1399 // is no reference back to the phi - need a graph walk
1400 // to determine if it is in a loop;
1401 // UnsafeLoop - unsafe case when the phi references itself directly or through
1402 // unsafe data node.
1403 // Note: a safe data node is a node which could/never reference itself during
1404 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1405 // I mark Phi nodes as safe node not only because they can reference itself
1406 // but also to prevent mistaking the fallthrough case inside an outer loop
1407 // as dead loop when the phi references itselfs through an other phi.
1408 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1409 // It is unsafe loop if the phi node references itself directly.
1410 if (in == (Node*)this)
1411 return UnsafeLoop; // Unsafe loop
1412 // Unsafe loop if the phi node references itself through an unsafe data node.
1413 // Exclude cases with null inputs or data nodes which could reference
1414 // itself (safe for dead loops).
1415 if (in != NULL && !in->is_dead_loop_safe()) {
1416 // Check inputs of phi's inputs also.
1417 // It is much less expensive then full graph walk.
1418 uint cnt = in->req();
1419 for (uint i = 1; i < cnt; ++i) {
1420 Node* m = in->in(i);
1421 if (m == (Node*)this)
1422 return UnsafeLoop; // Unsafe loop
1423 if (m != NULL && !m->is_dead_loop_safe()) {
1424 // Check the most common case (about 30% of all cases):
1425 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1426 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1427 if (m1 == (Node*)this)
1428 return UnsafeLoop; // Unsafe loop
1429 if (m1 != NULL && m1 == m->in(2) &&
1430 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1431 continue; // Safe case
1432 }
1433 // The phi references an unsafe node - need full analysis.
1434 return Unsafe;
1435 }
1436 }
1437 }
1438 return Safe; // Safe case - we can optimize the phi node.
1439 }
1440
1441 //------------------------------is_unsafe_data_reference-----------------------
1442 // If phi can be reached through the data input - it is data loop.
1443 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1444 assert(req() > 1, "");
1445 // First, check simple cases when phi references itself directly or
1446 // through an other node.
1447 LoopSafety safety = simple_data_loop_check(in);
1448 if (safety == UnsafeLoop)
1449 return true; // phi references itself - unsafe loop
1450 else if (safety == Safe)
1451 return false; // Safe case - phi could be replaced with the unique input.
1452
1453 // Unsafe case when we should go through data graph to determine
1454 // if the phi references itself.
1455
1456 ResourceMark rm;
1457
1458 Arena *a = Thread::current()->resource_area();
1459 Node_List nstack(a);
1460 VectorSet visited(a);
1461
1462 nstack.push(in); // Start with unique input.
1463 visited.set(in->_idx);
1464 while (nstack.size() != 0) {
1465 Node* n = nstack.pop();
1466 uint cnt = n->req();
1467 for (uint i = 1; i < cnt; i++) { // Only data paths
1468 Node* m = n->in(i);
1469 if (m == (Node*)this) {
1470 return true; // Data loop
1471 }
1472 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1473 if (!visited.test_set(m->_idx))
1474 nstack.push(m);
1475 }
1476 }
1477 }
1478 return false; // The phi is not reachable from its inputs
1479 }
1480
1481
1482 //------------------------------Ideal------------------------------------------
1483 // Return a node which is more "ideal" than the current node. Must preserve
1484 // the CFG, but we can still strip out dead paths.
1485 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1486 // The next should never happen after 6297035 fix.
1487 if( is_copy() ) // Already degraded to a Copy ?
1488 return NULL; // No change
1489
1490 Node *r = in(0); // RegionNode
1491 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1492
1493 // Note: During parsing, phis are often transformed before their regions.
1494 // This means we have to use type_or_null to defend against untyped regions.
1495 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1496 return NULL; // No change
1497
1498 Node *top = phase->C->top();
1499
1500 // The are 2 situations when only one valid phi's input is left
1501 // (in addition to Region input).
1502 // One: region is not loop - replace phi with this input.
1503 // Two: region is loop - replace phi with top since this data path is dead
1504 // and we need to break the dead data loop.
1505 Node* progress = NULL; // Record if any progress made
1506 for( uint j = 1; j < req(); ++j ){ // For all paths in
1507 // Check unreachable control paths
1508 Node* rc = r->in(j);
1509 Node* n = in(j); // Get the input
1510 if (rc == NULL || phase->type(rc) == Type::TOP) {
1511 if (n != top) { // Not already top?
1512 set_req(j, top); // Nuke it down
1513 progress = this; // Record progress
1514 }
1515 }
1516 }
1517
1518 Node* uin = unique_input(phase);
1519 if (uin == top) { // Simplest case: no alive inputs.
1520 if (can_reshape) // IGVN transformation
1521 return top;
1522 else
1523 return NULL; // Identity will return TOP
1524 } else if (uin != NULL) {
1525 // Only one not-NULL unique input path is left.
1526 // Determine if this input is backedge of a loop.
1527 // (Skip new phis which have no uses and dead regions).
1528 if( outcnt() > 0 && r->in(0) != NULL ) {
1529 // First, take the short cut when we know it is a loop and
1530 // the EntryControl data path is dead.
1531 assert(!r->is_Loop() || r->req() == 3, "Loop node should have 3 inputs");
1532 // Then, check if there is a data loop when phi references itself directly
1533 // or through other data nodes.
1534 if( r->is_Loop() && !phase->eqv_uncast(uin, in(LoopNode::EntryControl)) ||
1535 !r->is_Loop() && is_unsafe_data_reference(uin) ) {
1536 // Break this data loop to avoid creation of a dead loop.
1537 if (can_reshape) {
1538 return top;
1539 } else {
1540 // We can't return top if we are in Parse phase - cut inputs only
1541 // let Identity to handle the case.
1542 replace_edge(uin, top);
1543 return NULL;
1544 }
1545 }
1546 }
1547
1548 // One unique input.
1549 debug_only(Node* ident = Identity(phase));
1550 // The unique input must eventually be detected by the Identity call.
1551 #ifdef ASSERT
1552 if (ident != uin && !ident->is_top()) {
1553 // print this output before failing assert
1554 r->dump(3);
1555 this->dump(3);
1556 ident->dump();
1557 uin->dump();
1558 }
1559 #endif
1560 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1561 return NULL;
1562 }
1563
1564
1565 Node* opt = NULL;
1566 int true_path = is_diamond_phi();
1567 if( true_path != 0 ) {
1568 // Check for CMove'ing identity. If it would be unsafe,
1569 // handle it here. In the safe case, let Identity handle it.
1570 Node* unsafe_id = is_cmove_id(phase, true_path);
1571 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1572 opt = unsafe_id;
1573
1574 // Check for simple convert-to-boolean pattern
1575 if( opt == NULL )
1576 opt = is_x2logic(phase, this, true_path);
1577
1578 // Check for absolute value
1579 if( opt == NULL )
1580 opt = is_absolute(phase, this, true_path);
1581
1582 // Check for conditional add
1583 if( opt == NULL && can_reshape )
1584 opt = is_cond_add(phase, this, true_path);
1585
1586 // These 4 optimizations could subsume the phi:
1587 // have to check for a dead data loop creation.
1588 if( opt != NULL ) {
1589 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1590 // Found dead loop.
1591 if( can_reshape )
1592 return top;
1593 // We can't return top if we are in Parse phase - cut inputs only
1594 // to stop further optimizations for this phi. Identity will return TOP.
1595 assert(req() == 3, "only diamond merge phi here");
1596 set_req(1, top);
1597 set_req(2, top);
1598 return NULL;
1599 } else {
1600 return opt;
1601 }
1602 }
1603 }
1604
1605 // Check for merging identical values and split flow paths
1606 if (can_reshape) {
1607 opt = split_flow_path(phase, this);
1608 // This optimization only modifies phi - don't need to check for dead loop.
1609 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1610 if (opt != NULL) return opt;
1611 }
1612
1613 // Split phis through memory merges, so that the memory merges will go away.
1614 // Piggy-back this transformation on the search for a unique input....
1615 // It will be as if the merged memory is the unique value of the phi.
1616 // (Do not attempt this optimization unless parsing is complete.
1617 // It would make the parser's memory-merge logic sick.)
1618 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1619 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1620 // see if this phi should be sliced
1621 uint merge_width = 0;
1622 bool saw_self = false;
1623 for( uint i=1; i<req(); ++i ) {// For all paths in
1624 Node *ii = in(i);
1625 if (ii->is_MergeMem()) {
1626 MergeMemNode* n = ii->as_MergeMem();
1627 merge_width = MAX2(merge_width, n->req());
1628 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1629 }
1630 }
1631
1632 // This restriction is temporarily necessary to ensure termination:
1633 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1634
1635 if (merge_width > Compile::AliasIdxRaw) {
1636 // found at least one non-empty MergeMem
1637 const TypePtr* at = adr_type();
1638 if (at != TypePtr::BOTTOM) {
1639 // Patch the existing phi to select an input from the merge:
1640 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1641 // Phi:AT1(...m1...)
1642 int alias_idx = phase->C->get_alias_index(at);
1643 for (uint i=1; i<req(); ++i) {
1644 Node *ii = in(i);
1645 if (ii->is_MergeMem()) {
1646 MergeMemNode* n = ii->as_MergeMem();
1647 // compress paths and change unreachable cycles to TOP
1648 // If not, we can update the input infinitely along a MergeMem cycle
1649 // Equivalent code is in MemNode::Ideal_common
1650 Node *m = phase->transform(n);
1651 // If tranformed to a MergeMem, get the desired slice
1652 // Otherwise the returned node represents memory for every slice
1653 Node *new_mem = (m->is_MergeMem()) ?
1654 m->as_MergeMem()->memory_at(alias_idx) : m;
1655 // Update input if it is progress over what we have now
1656 if (new_mem != ii) {
1657 set_req(i, new_mem);
1658 progress = this;
1659 }
1660 }
1661 }
1662 } else {
1663 // We know that at least one MergeMem->base_memory() == this
1664 // (saw_self == true). If all other inputs also references this phi
1665 // (directly or through data nodes) - it is dead loop.
1666 bool saw_safe_input = false;
1667 for (uint j = 1; j < req(); ++j) {
1668 Node *n = in(j);
1669 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1670 continue; // skip known cases
1671 if (!is_unsafe_data_reference(n)) {
1672 saw_safe_input = true; // found safe input
1673 break;
1674 }
1675 }
1676 if (!saw_safe_input)
1677 return top; // all inputs reference back to this phi - dead loop
1678
1679 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1680 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1681 PhaseIterGVN *igvn = phase->is_IterGVN();
1682 Node* hook = new (phase->C, 1) Node(1);
1683 PhiNode* new_base = (PhiNode*) clone();
1684 // Must eagerly register phis, since they participate in loops.
1685 if (igvn) {
1686 igvn->register_new_node_with_optimizer(new_base);
1687 hook->add_req(new_base);
1688 }
1689 MergeMemNode* result = MergeMemNode::make(phase->C, new_base);
1690 for (uint i = 1; i < req(); ++i) {
1691 Node *ii = in(i);
1692 if (ii->is_MergeMem()) {
1693 MergeMemNode* n = ii->as_MergeMem();
1694 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1695 // If we have not seen this slice yet, make a phi for it.
1696 bool made_new_phi = false;
1697 if (mms.is_empty()) {
1698 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1699 made_new_phi = true;
1700 if (igvn) {
1701 igvn->register_new_node_with_optimizer(new_phi);
1702 hook->add_req(new_phi);
1703 }
1704 mms.set_memory(new_phi);
1705 }
1706 Node* phi = mms.memory();
1707 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1708 phi->set_req(i, mms.memory2());
1709 }
1710 }
1711 }
1712 // Distribute all self-loops.
1713 { // (Extra braces to hide mms.)
1714 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1715 Node* phi = mms.memory();
1716 for (uint i = 1; i < req(); ++i) {
1717 if (phi->in(i) == this) phi->set_req(i, phi);
1718 }
1719 }
1720 }
1721 // now transform the new nodes, and return the mergemem
1722 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1723 Node* phi = mms.memory();
1724 mms.set_memory(phase->transform(phi));
1725 }
1726 if (igvn) { // Unhook.
1727 igvn->hash_delete(hook);
1728 for (uint i = 1; i < hook->req(); i++) {
1729 hook->set_req(i, NULL);
1730 }
1731 }
1732 // Replace self with the result.
1733 return result;
1734 }
1735 }
1736 //
1737 // Other optimizations on the memory chain
1738 //
1739 const TypePtr* at = adr_type();
1740 for( uint i=1; i<req(); ++i ) {// For all paths in
1741 Node *ii = in(i);
1742 Node *new_in = MemNode::optimize_memory_chain(ii, at, phase);
1743 if (ii != new_in ) {
1744 set_req(i, new_in);
1745 progress = this;
1746 }
1747 }
1748 }
1749
1750 return progress; // Return any progress
1751 }
1752
1753 //------------------------------out_RegMask------------------------------------
1754 const RegMask &PhiNode::in_RegMask(uint i) const {
1755 return i ? out_RegMask() : RegMask::Empty;
1756 }
1757
1758 const RegMask &PhiNode::out_RegMask() const {
1759 uint ideal_reg = Matcher::base2reg[_type->base()];
1760 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
1761 if( ideal_reg == 0 ) return RegMask::Empty;
1762 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
1763 }
1764
1765 #ifndef PRODUCT
1766 void PhiNode::dump_spec(outputStream *st) const {
1767 TypeNode::dump_spec(st);
1768 if (in(0) != NULL &&
1769 in(0)->is_CountedLoop() &&
1770 in(0)->as_CountedLoop()->phi() == this) {
1771 st->print(" #tripcount");
1772 }
1773 }
1774 #endif
1775
1776
1777 //=============================================================================
1778 const Type *GotoNode::Value( PhaseTransform *phase ) const {
1779 // If the input is reachable, then we are executed.
1780 // If the input is not reachable, then we are not executed.
1781 return phase->type(in(0));
1782 }
1783
1784 Node *GotoNode::Identity( PhaseTransform *phase ) {
1785 return in(0); // Simple copy of incoming control
1786 }
1787
1788 const RegMask &GotoNode::out_RegMask() const {
1789 return RegMask::Empty;
1790 }
1791
1792 //=============================================================================
1793 const RegMask &JumpNode::out_RegMask() const {
1794 return RegMask::Empty;
1795 }
1796
1797 //=============================================================================
1798 const RegMask &JProjNode::out_RegMask() const {
1799 return RegMask::Empty;
1800 }
1801
1802 //=============================================================================
1803 const RegMask &CProjNode::out_RegMask() const {
1804 return RegMask::Empty;
1805 }
1806
1807
1808
1809 //=============================================================================
1810
1811 uint PCTableNode::hash() const { return Node::hash() + _size; }
1812 uint PCTableNode::cmp( const Node &n ) const
1813 { return _size == ((PCTableNode&)n)._size; }
1814
1815 const Type *PCTableNode::bottom_type() const {
1816 const Type** f = TypeTuple::fields(_size);
1817 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
1818 return TypeTuple::make(_size, f);
1819 }
1820
1821 //------------------------------Value------------------------------------------
1822 // Compute the type of the PCTableNode. If reachable it is a tuple of
1823 // Control, otherwise the table targets are not reachable
1824 const Type *PCTableNode::Value( PhaseTransform *phase ) const {
1825 if( phase->type(in(0)) == Type::CONTROL )
1826 return bottom_type();
1827 return Type::TOP; // All paths dead? Then so are we
1828 }
1829
1830 //------------------------------Ideal------------------------------------------
1831 // Return a node which is more "ideal" than the current node. Strip out
1832 // control copies
1833 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1834 return remove_dead_region(phase, can_reshape) ? this : NULL;
1835 }
1836
1837 //=============================================================================
1838 uint JumpProjNode::hash() const {
1839 return Node::hash() + _dest_bci;
1840 }
1841
1842 uint JumpProjNode::cmp( const Node &n ) const {
1843 return ProjNode::cmp(n) &&
1844 _dest_bci == ((JumpProjNode&)n)._dest_bci;
1845 }
1846
1847 #ifndef PRODUCT
1848 void JumpProjNode::dump_spec(outputStream *st) const {
1849 ProjNode::dump_spec(st);
1850 st->print("@bci %d ",_dest_bci);
1851 }
1852 #endif
1853
1854 //=============================================================================
1855 //------------------------------Value------------------------------------------
1856 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
1857 // have the default "fall_through_index" path.
1858 const Type *CatchNode::Value( PhaseTransform *phase ) const {
1859 // Unreachable? Then so are all paths from here.
1860 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
1861 // First assume all paths are reachable
1862 const Type** f = TypeTuple::fields(_size);
1863 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
1864 // Identify cases that will always throw an exception
1865 // () rethrow call
1866 // () virtual or interface call with NULL receiver
1867 // () call is a check cast with incompatible arguments
1868 if( in(1)->is_Proj() ) {
1869 Node *i10 = in(1)->in(0);
1870 if( i10->is_Call() ) {
1871 CallNode *call = i10->as_Call();
1872 // Rethrows always throw exceptions, never return
1873 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
1874 f[CatchProjNode::fall_through_index] = Type::TOP;
1875 } else if( call->req() > TypeFunc::Parms ) {
1876 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
1877 // Check for null reciever to virtual or interface calls
1878 if( call->is_CallDynamicJava() &&
1879 arg0->higher_equal(TypePtr::NULL_PTR) ) {
1880 f[CatchProjNode::fall_through_index] = Type::TOP;
1881 }
1882 } // End of if not a runtime stub
1883 } // End of if have call above me
1884 } // End of slot 1 is not a projection
1885 return TypeTuple::make(_size, f);
1886 }
1887
1888 //=============================================================================
1889 uint CatchProjNode::hash() const {
1890 return Node::hash() + _handler_bci;
1891 }
1892
1893
1894 uint CatchProjNode::cmp( const Node &n ) const {
1895 return ProjNode::cmp(n) &&
1896 _handler_bci == ((CatchProjNode&)n)._handler_bci;
1897 }
1898
1899
1900 //------------------------------Identity---------------------------------------
1901 // If only 1 target is possible, choose it if it is the main control
1902 Node *CatchProjNode::Identity( PhaseTransform *phase ) {
1903 // If my value is control and no other value is, then treat as ID
1904 const TypeTuple *t = phase->type(in(0))->is_tuple();
1905 if (t->field_at(_con) != Type::CONTROL) return this;
1906 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
1907 // also remove any exception table entry. Thus we must know the call
1908 // feeding the Catch will not really throw an exception. This is ok for
1909 // the main fall-thru control (happens when we know a call can never throw
1910 // an exception) or for "rethrow", because a further optimnization will
1911 // yank the rethrow (happens when we inline a function that can throw an
1912 // exception and the caller has no handler). Not legal, e.g., for passing
1913 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
1914 // These cases MUST throw an exception via the runtime system, so the VM
1915 // will be looking for a table entry.
1916 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
1917 CallNode *call;
1918 if (_con != TypeFunc::Control && // Bail out if not the main control.
1919 !(proj->is_Proj() && // AND NOT a rethrow
1920 proj->in(0)->is_Call() &&
1921 (call = proj->in(0)->as_Call()) &&
1922 call->entry_point() == OptoRuntime::rethrow_stub()))
1923 return this;
1924
1925 // Search for any other path being control
1926 for (uint i = 0; i < t->cnt(); i++) {
1927 if (i != _con && t->field_at(i) == Type::CONTROL)
1928 return this;
1929 }
1930 // Only my path is possible; I am identity on control to the jump
1931 return in(0)->in(0);
1932 }
1933
1934
1935 #ifndef PRODUCT
1936 void CatchProjNode::dump_spec(outputStream *st) const {
1937 ProjNode::dump_spec(st);
1938 st->print("@bci %d ",_handler_bci);
1939 }
1940 #endif
1941
1942 //=============================================================================
1943 //------------------------------Identity---------------------------------------
1944 // Check for CreateEx being Identity.
1945 Node *CreateExNode::Identity( PhaseTransform *phase ) {
1946 if( phase->type(in(1)) == Type::TOP ) return in(1);
1947 if( phase->type(in(0)) == Type::TOP ) return in(0);
1948 // We only come from CatchProj, unless the CatchProj goes away.
1949 // If the CatchProj is optimized away, then we just carry the
1950 // exception oop through.
1951 CallNode *call = in(1)->in(0)->as_Call();
1952
1953 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
1954 ? this
1955 : call->in(TypeFunc::Parms);
1956 }
1957
1958 //=============================================================================
1959 #ifndef PRODUCT
1960 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
1961 st->print("%s", Name());
1962 }
1963 #endif