1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)cfgnode.cpp 1.262 08/11/24 12:22:57 JVM"
3 #endif
4 /*
5 * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 // Portions of code courtesy of Clifford Click
29
30 // Optimization - Graph Style
31
32 #include "incls/_precompiled.incl"
33 #include "incls/_cfgnode.cpp.incl"
34
35 //=============================================================================
36 //------------------------------Value------------------------------------------
37 // Compute the type of the RegionNode.
38 const Type *RegionNode::Value( PhaseTransform *phase ) const {
39 for( uint i=1; i<req(); ++i ) { // For all paths in
40 Node *n = in(i); // Get Control source
41 if( !n ) continue; // Missing inputs are TOP
42 if( phase->type(n) == Type::CONTROL )
43 return Type::CONTROL;
44 }
45 return Type::TOP; // All paths dead? Then so are we
46 }
47
48 //------------------------------Identity---------------------------------------
49 // Check for Region being Identity.
50 Node *RegionNode::Identity( PhaseTransform *phase ) {
51 // Cannot have Region be an identity, even if it has only 1 input.
52 // Phi users cannot have their Region input folded away for them,
53 // since they need to select the proper data input
54 return this;
55 }
56
57 //------------------------------merge_region-----------------------------------
58 // If a Region flows into a Region, merge into one big happy merge. This is
59 // hard to do if there is stuff that has to happen
60 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
61 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
62 return NULL;
63 Node *progress = NULL; // Progress flag
64 PhaseIterGVN *igvn = phase->is_IterGVN();
65
66 uint rreq = region->req();
67 for( uint i = 1; i < rreq; i++ ) {
68 Node *r = region->in(i);
69 if( r && r->Opcode() == Op_Region && // Found a region?
70 r->in(0) == r && // Not already collapsed?
71 r != region && // Avoid stupid situations
72 r->outcnt() == 2 ) { // Self user and 'region' user only?
73 assert(!r->as_Region()->has_phi(), "no phi users");
74 if( !progress ) { // No progress
75 if (region->has_phi()) {
76 return NULL; // Only flatten if no Phi users
77 // igvn->hash_delete( phi );
78 }
79 igvn->hash_delete( region );
80 progress = region; // Making progress
81 }
82 igvn->hash_delete( r );
83
84 // Append inputs to 'r' onto 'region'
85 for( uint j = 1; j < r->req(); j++ ) {
86 // Move an input from 'r' to 'region'
87 region->add_req(r->in(j));
88 r->set_req(j, phase->C->top());
89 // Update phis of 'region'
90 //for( uint k = 0; k < max; k++ ) {
91 // Node *phi = region->out(k);
92 // if( phi->is_Phi() ) {
93 // phi->add_req(phi->in(i));
94 // }
95 //}
96
97 rreq++; // One more input to Region
98 } // Found a region to merge into Region
99 // Clobber pointer to the now dead 'r'
100 region->set_req(i, phase->C->top());
101 }
102 }
103
104 return progress;
105 }
106
107
108
109 //--------------------------------has_phi--------------------------------------
110 // Helper function: Return any PhiNode that uses this region or NULL
111 PhiNode* RegionNode::has_phi() const {
112 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
113 Node* phi = fast_out(i);
114 if (phi->is_Phi()) { // Check for Phi users
115 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
116 return phi->as_Phi(); // this one is good enough
117 }
118 }
119
120 return NULL;
121 }
122
123
124 //-----------------------------has_unique_phi----------------------------------
125 // Helper function: Return the only PhiNode that uses this region or NULL
126 PhiNode* RegionNode::has_unique_phi() const {
127 // Check that only one use is a Phi
128 PhiNode* only_phi = NULL;
129 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
130 Node* phi = fast_out(i);
131 if (phi->is_Phi()) { // Check for Phi users
132 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
133 if (only_phi == NULL) {
134 only_phi = phi->as_Phi();
135 } else {
136 return NULL; // multiple phis
137 }
138 }
139 }
140
141 return only_phi;
142 }
143
144
145 //------------------------------check_phi_clipping-----------------------------
146 // Helper function for RegionNode's identification of FP clipping
147 // Check inputs to the Phi
148 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
149 min = NULL;
150 max = NULL;
151 val = NULL;
152 min_idx = 0;
153 max_idx = 0;
154 val_idx = 0;
155 uint phi_max = phi->req();
156 if( phi_max == 4 ) {
157 for( uint j = 1; j < phi_max; ++j ) {
158 Node *n = phi->in(j);
159 int opcode = n->Opcode();
160 switch( opcode ) {
161 case Op_ConI:
162 {
163 if( min == NULL ) {
164 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
165 min_idx = j;
166 } else {
167 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
168 max_idx = j;
169 if( min->get_int() > max->get_int() ) {
170 // Swap min and max
171 ConNode *temp;
172 uint temp_idx;
173 temp = min; min = max; max = temp;
174 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
175 }
176 }
177 }
178 break;
179 default:
180 {
181 val = n;
182 val_idx = j;
183 }
184 break;
185 }
186 }
187 }
188 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
189 }
190
191
192 //------------------------------check_if_clipping------------------------------
193 // Helper function for RegionNode's identification of FP clipping
194 // Check that inputs to Region come from two IfNodes,
195 //
196 // If
197 // False True
198 // If |
199 // False True |
200 // | | |
201 // RegionNode_inputs
202 //
203 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
204 top_if = NULL;
205 bot_if = NULL;
206
207 // Check control structure above RegionNode for (if ( if ) )
208 Node *in1 = region->in(1);
209 Node *in2 = region->in(2);
210 Node *in3 = region->in(3);
211 // Check that all inputs are projections
212 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
213 Node *in10 = in1->in(0);
214 Node *in20 = in2->in(0);
215 Node *in30 = in3->in(0);
216 // Check that #1 and #2 are ifTrue and ifFalse from same If
217 if( in10 != NULL && in10->is_If() &&
218 in20 != NULL && in20->is_If() &&
219 in30 != NULL && in30->is_If() && in10 == in20 &&
220 (in1->Opcode() != in2->Opcode()) ) {
221 Node *in100 = in10->in(0);
222 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
223 // Check that control for in10 comes from other branch of IF from in3
224 if( in1000 != NULL && in1000->is_If() &&
225 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
226 // Control pattern checks
227 top_if = (IfNode*)in1000;
228 bot_if = (IfNode*)in10;
229 }
230 }
231 }
232
233 return (top_if != NULL);
234 }
235
236
237 //------------------------------check_convf2i_clipping-------------------------
238 // Helper function for RegionNode's identification of FP clipping
239 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
240 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
241 convf2i = NULL;
242
243 // Check for the RShiftNode
244 Node *rshift = phi->in(idx);
245 assert( rshift, "Previous checks ensure phi input is present");
246 if( rshift->Opcode() != Op_RShiftI ) { return false; }
247
248 // Check for the LShiftNode
249 Node *lshift = rshift->in(1);
250 assert( lshift, "Previous checks ensure phi input is present");
251 if( lshift->Opcode() != Op_LShiftI ) { return false; }
252
253 // Check for the ConvF2INode
254 Node *conv = lshift->in(1);
255 if( conv->Opcode() != Op_ConvF2I ) { return false; }
256
257 // Check that shift amounts are only to get sign bits set after F2I
258 jint max_cutoff = max->get_int();
259 jint min_cutoff = min->get_int();
260 jint left_shift = lshift->in(2)->get_int();
261 jint right_shift = rshift->in(2)->get_int();
262 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
263 if( left_shift != right_shift ||
264 0 > left_shift || left_shift >= BitsPerJavaInteger ||
265 max_post_shift < max_cutoff ||
266 max_post_shift < -min_cutoff ) {
267 // Shifts are necessary but current transformation eliminates them
268 return false;
269 }
270
271 // OK to return the result of ConvF2I without shifting
272 convf2i = (ConvF2INode*)conv;
273 return true;
274 }
275
276
277 //------------------------------check_compare_clipping-------------------------
278 // Helper function for RegionNode's identification of FP clipping
279 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
280 Node *i1 = iff->in(1);
281 if ( !i1->is_Bool() ) { return false; }
282 BoolNode *bool1 = i1->as_Bool();
283 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
284 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
285 const Node *cmpF = bool1->in(1);
286 if( cmpF->Opcode() != Op_CmpF ) { return false; }
287 // Test that the float value being compared against
288 // is equivalent to the int value used as a limit
289 Node *nodef = cmpF->in(2);
290 if( nodef->Opcode() != Op_ConF ) { return false; }
291 jfloat conf = nodef->getf();
292 jint coni = limit->get_int();
293 if( ((int)conf) != coni ) { return false; }
294 input = cmpF->in(1);
295 return true;
296 }
297
298 //------------------------------is_unreachable_region--------------------------
299 // Find if the Region node is reachable from the root.
300 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
301 assert(req() == 2, "");
302
303 // First, cut the simple case of fallthrough region when NONE of
304 // region's phis references itself directly or through a data node.
305 uint max = outcnt();
306 uint i;
307 for (i = 0; i < max; i++) {
308 Node* phi = raw_out(i);
309 if (phi != NULL && phi->is_Phi()) {
310 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
311 if (phi->outcnt() == 0)
312 continue; // Safe case - no loops
313 if (phi->outcnt() == 1) {
314 Node* u = phi->raw_out(0);
315 // Skip if only one use is an other Phi or Call or Uncommon trap.
316 // It is safe to consider this case as fallthrough.
317 if (u != NULL && (u->is_Phi() || u->is_CFG()))
318 continue;
319 }
320 // Check when phi references itself directly or through an other node.
321 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
322 break; // Found possible unsafe data loop.
323 }
324 }
325 if (i >= max)
326 return false; // An unsafe case was NOT found - don't need graph walk.
327
328 // Unsafe case - check if the Region node is reachable from root.
329 ResourceMark rm;
330
331 Arena *a = Thread::current()->resource_area();
332 Node_List nstack(a);
333 VectorSet visited(a);
334
335 // Mark all control nodes reachable from root outputs
336 Node *n = (Node*)phase->C->root();
337 nstack.push(n);
338 visited.set(n->_idx);
339 while (nstack.size() != 0) {
340 n = nstack.pop();
341 uint max = n->outcnt();
342 for (uint i = 0; i < max; i++) {
343 Node* m = n->raw_out(i);
344 if (m != NULL && m->is_CFG()) {
345 if (phase->eqv(m, this)) {
346 return false; // We reached the Region node - it is not dead.
347 }
348 if (!visited.test_set(m->_idx))
349 nstack.push(m);
350 }
351 }
352 }
353
354 return true; // The Region node is unreachable - it is dead.
355 }
356
357 //------------------------------Ideal------------------------------------------
358 // Return a node which is more "ideal" than the current node. Must preserve
359 // the CFG, but we can still strip out dead paths.
360 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
361 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
362 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
363
364 // Check for RegionNode with no Phi users and both inputs come from either
365 // arm of the same IF. If found, then the control-flow split is useless.
366 bool has_phis = false;
367 if (can_reshape) { // Need DU info to check for Phi users
368 has_phis = (has_phi() != NULL); // Cache result
369 if (!has_phis) { // No Phi users? Nothing merging?
370 for (uint i = 1; i < req()-1; i++) {
371 Node *if1 = in(i);
372 if( !if1 ) continue;
373 Node *iff = if1->in(0);
374 if( !iff || !iff->is_If() ) continue;
375 for( uint j=i+1; j<req(); j++ ) {
376 if( in(j) && in(j)->in(0) == iff &&
377 if1->Opcode() != in(j)->Opcode() ) {
378 // Add the IF Projections to the worklist. They (and the IF itself)
379 // will be eliminated if dead.
380 phase->is_IterGVN()->add_users_to_worklist(iff);
381 set_req(i, iff->in(0));// Skip around the useless IF diamond
382 set_req(j, NULL);
383 return this; // Record progress
384 }
385 }
386 }
387 }
388 }
389
390 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
391 // degrades to a copy.
392 bool add_to_worklist = false;
393 int cnt = 0; // Count of values merging
394 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
395 int del_it = 0; // The last input path we delete
396 // For all inputs...
397 for( uint i=1; i<req(); ++i ){// For all paths in
398 Node *n = in(i); // Get the input
399 if( n != NULL ) {
400 // Remove useless control copy inputs
401 if( n->is_Region() && n->as_Region()->is_copy() ) {
402 set_req(i, n->nonnull_req());
403 i--;
404 continue;
405 }
406 if( n->is_Proj() ) { // Remove useless rethrows
407 Node *call = n->in(0);
408 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
409 set_req(i, call->in(0));
410 i--;
411 continue;
412 }
413 }
414 if( phase->type(n) == Type::TOP ) {
415 set_req(i, NULL); // Ignore TOP inputs
416 i--;
417 continue;
418 }
419 cnt++; // One more value merging
420
421 } else if (can_reshape) { // Else found dead path with DU info
422 PhaseIterGVN *igvn = phase->is_IterGVN();
423 del_req(i); // Yank path from self
424 del_it = i;
425 uint max = outcnt();
426 DUIterator j;
427 bool progress = true;
428 while(progress) { // Need to establish property over all users
429 progress = false;
430 for (j = outs(); has_out(j); j++) {
431 Node *n = out(j);
432 if( n->req() != req() && n->is_Phi() ) {
433 assert( n->in(0) == this, "" );
434 igvn->hash_delete(n); // Yank from hash before hacking edges
435 n->set_req_X(i,NULL,igvn);// Correct DU info
436 n->del_req(i); // Yank path from Phis
437 if( max != outcnt() ) {
438 progress = true;
439 j = refresh_out_pos(j);
440 max = outcnt();
441 }
442 }
443 }
444 }
445 add_to_worklist = true;
446 i--;
447 }
448 }
449
450 if (can_reshape && cnt == 1) {
451 // Is it dead loop?
452 // If it is LoopNopde it had 2 (+1 itself) inputs and
453 // one of them was cut. The loop is dead if it was EntryContol.
454 assert(!this->is_Loop() || cnt_orig == 3, "Loop node should have 3 inputs");
455 if (this->is_Loop() && del_it == LoopNode::EntryControl ||
456 !this->is_Loop() && has_phis && is_unreachable_region(phase)) {
457 // Yes, the region will be removed during the next step below.
458 // Cut the backedge input and remove phis since no data paths left.
459 // We don't cut outputs to other nodes here since we need to put them
460 // on the worklist.
461 del_req(1);
462 cnt = 0;
463 assert( req() == 1, "no more inputs expected" );
464 uint max = outcnt();
465 bool progress = true;
466 Node *top = phase->C->top();
467 PhaseIterGVN *igvn = phase->is_IterGVN();
468 DUIterator j;
469 while(progress) {
470 progress = false;
471 for (j = outs(); has_out(j); j++) {
472 Node *n = out(j);
473 if( n->is_Phi() ) {
474 assert( igvn->eqv(n->in(0), this), "" );
475 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
476 // Break dead loop data path.
477 // Eagerly replace phis with top to avoid phis copies generation.
478 igvn->add_users_to_worklist(n);
479 igvn->hash_delete(n); // Yank from hash before hacking edges
480 igvn->subsume_node(n, top);
481 if( max != outcnt() ) {
482 progress = true;
483 j = refresh_out_pos(j);
484 max = outcnt();
485 }
486 }
487 }
488 }
489 add_to_worklist = true;
490 }
491 }
492 if (add_to_worklist) {
493 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
494 }
495
496 if( cnt <= 1 ) { // Only 1 path in?
497 set_req(0, NULL); // Null control input for region copy
498 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
499 // No inputs or all inputs are NULL.
500 return NULL;
501 } else if (can_reshape) { // Optimization phase - remove the node
502 PhaseIterGVN *igvn = phase->is_IterGVN();
503 Node *parent_ctrl;
504 if( cnt == 0 ) {
505 assert( req() == 1, "no inputs expected" );
506 // During IGVN phase such region will be subsumed by TOP node
507 // so region's phis will have TOP as control node.
508 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
509 // Also set other user's input to top.
510 parent_ctrl = phase->C->top();
511 } else {
512 // The fallthrough case since we already checked dead loops above.
513 parent_ctrl = in(1);
514 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
515 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
516 }
517 if (!add_to_worklist)
518 igvn->add_users_to_worklist(this); // Check for further allowed opts
519 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
520 Node* n = last_out(i);
521 igvn->hash_delete(n); // Remove from worklist before modifying edges
522 if( n->is_Phi() ) { // Collapse all Phis
523 // Eagerly replace phis to avoid copies generation.
524 igvn->add_users_to_worklist(n);
525 igvn->hash_delete(n); // Yank from hash before hacking edges
526 if( cnt == 0 ) {
527 assert( n->req() == 1, "No data inputs expected" );
528 igvn->subsume_node(n, parent_ctrl); // replaced by top
529 } else {
530 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
531 Node* in1 = n->in(1); // replaced by unique input
532 if( n->as_Phi()->is_unsafe_data_reference(in1) )
533 in1 = phase->C->top(); // replaced by top
534 igvn->subsume_node(n, in1);
535 }
536 }
537 else if( n->is_Region() ) { // Update all incoming edges
538 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
539 uint uses_found = 0;
540 for( uint k=1; k < n->req(); k++ ) {
541 if( n->in(k) == this ) {
542 n->set_req(k, parent_ctrl);
543 uses_found++;
544 }
545 }
546 if( uses_found > 1 ) { // (--i) done at the end of the loop.
547 i -= (uses_found - 1);
548 }
549 }
550 else {
551 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
552 n->set_req(0, parent_ctrl);
553 }
554 #ifdef ASSERT
555 for( uint k=0; k < n->req(); k++ ) {
556 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
557 }
558 #endif
559 }
560 // Remove the RegionNode itself from DefUse info
561 igvn->remove_dead_node(this);
562 return NULL;
563 }
564 return this; // Record progress
565 }
566
567
568 // If a Region flows into a Region, merge into one big happy merge.
569 if (can_reshape) {
570 Node *m = merge_region(this, phase);
571 if (m != NULL) return m;
572 }
573
574 // Check if this region is the root of a clipping idiom on floats
575 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
576 // Check that only one use is a Phi and that it simplifies to two constants +
577 PhiNode* phi = has_unique_phi();
578 if (phi != NULL) { // One Phi user
579 // Check inputs to the Phi
580 ConNode *min;
581 ConNode *max;
582 Node *val;
583 uint min_idx;
584 uint max_idx;
585 uint val_idx;
586 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
587 IfNode *top_if;
588 IfNode *bot_if;
589 if( check_if_clipping( this, bot_if, top_if ) ) {
590 // Control pattern checks, now verify compares
591 Node *top_in = NULL; // value being compared against
592 Node *bot_in = NULL;
593 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
594 check_compare_clipping( false, top_if, max, top_in ) ) {
595 if( bot_in == top_in ) {
596 PhaseIterGVN *gvn = phase->is_IterGVN();
597 assert( gvn != NULL, "Only had DefUse info in IterGVN");
598 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
599
600 // Check for the ConvF2INode
601 ConvF2INode *convf2i;
602 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
603 convf2i->in(1) == bot_in ) {
604 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
605 // max test
606 Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, min ));
607 Node *boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::lt ));
608 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 ));
609 Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
610 Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
611 // min test
612 cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, max ));
613 boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::gt ));
614 iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
615 Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
616 ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
617 // update input edges to region node
618 set_req_X( min_idx, if_min, gvn );
619 set_req_X( max_idx, if_max, gvn );
620 set_req_X( val_idx, ifF, gvn );
621 // remove unnecessary 'LShiftI; RShiftI' idiom
622 gvn->hash_delete(phi);
623 phi->set_req_X( val_idx, convf2i, gvn );
624 gvn->hash_find_insert(phi);
625 // Return transformed region node
626 return this;
627 }
628 }
629 }
630 }
631 }
632 }
633 }
634
635 return NULL;
636 }
637
638
639
640 const RegMask &RegionNode::out_RegMask() const {
641 return RegMask::Empty;
642 }
643
644 // Find the one non-null required input. RegionNode only
645 Node *Node::nonnull_req() const {
646 assert( is_Region(), "" );
647 for( uint i = 1; i < _cnt; i++ )
648 if( in(i) )
649 return in(i);
650 ShouldNotReachHere();
651 return NULL;
652 }
653
654
655 //=============================================================================
656 // note that these functions assume that the _adr_type field is flattened
657 uint PhiNode::hash() const {
658 const Type* at = _adr_type;
659 return TypeNode::hash() + (at ? at->hash() : 0);
660 }
661 uint PhiNode::cmp( const Node &n ) const {
662 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
663 }
664 static inline
665 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
666 if (at == NULL || at == TypePtr::BOTTOM) return at;
667 return Compile::current()->alias_type(at)->adr_type();
668 }
669
670 //----------------------------make---------------------------------------------
671 // create a new phi with edges matching r and set (initially) to x
672 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
673 uint preds = r->req(); // Number of predecessor paths
674 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
675 PhiNode* p = new (Compile::current(), preds) PhiNode(r, t, at);
676 for (uint j = 1; j < preds; j++) {
677 // Fill in all inputs, except those which the region does not yet have
678 if (r->in(j) != NULL)
679 p->init_req(j, x);
680 }
681 return p;
682 }
683 PhiNode* PhiNode::make(Node* r, Node* x) {
684 const Type* t = x->bottom_type();
685 const TypePtr* at = NULL;
686 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
687 return make(r, x, t, at);
688 }
689 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
690 const Type* t = x->bottom_type();
691 const TypePtr* at = NULL;
692 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
693 return new (Compile::current(), r->req()) PhiNode(r, t, at);
694 }
695
696
697 //------------------------slice_memory-----------------------------------------
698 // create a new phi with narrowed memory type
699 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
700 PhiNode* mem = (PhiNode*) clone();
701 *(const TypePtr**)&mem->_adr_type = adr_type;
702 // convert self-loops, or else we get a bad graph
703 for (uint i = 1; i < req(); i++) {
704 if ((const Node*)in(i) == this) mem->set_req(i, mem);
705 }
706 mem->verify_adr_type();
707 return mem;
708 }
709
710 //------------------------verify_adr_type--------------------------------------
711 #ifdef ASSERT
712 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
713 if (visited.test_set(_idx)) return; //already visited
714
715 // recheck constructor invariants:
716 verify_adr_type(false);
717
718 // recheck local phi/phi consistency:
719 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
720 "adr_type must be consistent across phi nest");
721
722 // walk around
723 for (uint i = 1; i < req(); i++) {
724 Node* n = in(i);
725 if (n == NULL) continue;
726 const Node* np = in(i);
727 if (np->is_Phi()) {
728 np->as_Phi()->verify_adr_type(visited, at);
729 } else if (n->bottom_type() == Type::TOP
730 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
731 // ignore top inputs
732 } else {
733 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
734 // recheck phi/non-phi consistency at leaves:
735 assert((nat != NULL) == (at != NULL), "");
736 assert(nat == at || nat == TypePtr::BOTTOM,
737 "adr_type must be consistent at leaves of phi nest");
738 }
739 }
740 }
741
742 // Verify a whole nest of phis rooted at this one.
743 void PhiNode::verify_adr_type(bool recursive) const {
744 if (is_error_reported()) return; // muzzle asserts when debugging an error
745 if (Node::in_dump()) return; // muzzle asserts when printing
746
747 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
748
749 if (!VerifyAliases) return; // verify thoroughly only if requested
750
751 assert(_adr_type == flatten_phi_adr_type(_adr_type),
752 "Phi::adr_type must be pre-normalized");
753
754 if (recursive) {
755 VectorSet visited(Thread::current()->resource_area());
756 verify_adr_type(visited, _adr_type);
757 }
758 }
759 #endif
760
761
762 //------------------------------Value------------------------------------------
763 // Compute the type of the PhiNode
764 const Type *PhiNode::Value( PhaseTransform *phase ) const {
765 Node *r = in(0); // RegionNode
766 if( !r ) // Copy or dead
767 return in(1) ? phase->type(in(1)) : Type::TOP;
768
769 // Note: During parsing, phis are often transformed before their regions.
770 // This means we have to use type_or_null to defend against untyped regions.
771 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
772 return Type::TOP;
773
774 // Check for trip-counted loop. If so, be smarter.
775 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
776 if( l && l->can_be_counted_loop(phase) &&
777 ((const Node*)l->phi() == this) ) { // Trip counted loop!
778 // protect against init_trip() or limit() returning NULL
779 const Node *init = l->init_trip();
780 const Node *limit = l->limit();
781 if( init != NULL && limit != NULL && l->stride_is_con() ) {
782 const TypeInt *lo = init ->bottom_type()->isa_int();
783 const TypeInt *hi = limit->bottom_type()->isa_int();
784 if( lo && hi ) { // Dying loops might have TOP here
785 int stride = l->stride_con();
786 if( stride < 0 ) { // Down-counter loop
787 const TypeInt *tmp = lo; lo = hi; hi = tmp;
788 stride = -stride;
789 }
790 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
791 return TypeInt::make(lo->_lo,hi->_hi,3);
792 }
793 }
794 }
795
796 // Until we have harmony between classes and interfaces in the type
797 // lattice, we must tread carefully around phis which implicitly
798 // convert the one to the other.
799 const TypeInstPtr* ttip = _type->isa_instptr();
800 bool is_intf = false;
801 if (ttip != NULL) {
802 ciKlass* k = ttip->klass();
803 if (k->is_loaded() && k->is_interface())
804 is_intf = true;
805 }
806
807 // Default case: merge all inputs
808 const Type *t = Type::TOP; // Merged type starting value
809 for (uint i = 1; i < req(); ++i) {// For all paths in
810 // Reachable control path?
811 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
812 const Type* ti = phase->type(in(i));
813 // We assume that each input of an interface-valued Phi is a true
814 // subtype of that interface. This might not be true of the meet
815 // of all the input types. The lattice is not distributive in
816 // such cases. Ward off asserts in type.cpp by refusing to do
817 // meets between interfaces and proper classes.
818 const TypeInstPtr* tiip = ti->isa_instptr();
819 if (tiip) {
820 bool ti_is_intf = false;
821 ciKlass* k = tiip->klass();
822 if (k->is_loaded() && k->is_interface())
823 ti_is_intf = true;
824 if (is_intf != ti_is_intf)
825 { t = _type; break; }
826 }
827 t = t->meet(ti);
828 }
829 }
830
831 // The worst-case type (from ciTypeFlow) should be consistent with "t".
832 // That is, we expect that "t->higher_equal(_type)" holds true.
833 // There are various exceptions:
834 // - Inputs which are phis might in fact be widened unnecessarily.
835 // For example, an input might be a widened int while the phi is a short.
836 // - Inputs might be BotPtrs but this phi is dependent on a null check,
837 // and postCCP has removed the cast which encodes the result of the check.
838 // - The type of this phi is an interface, and the inputs are classes.
839 // - Value calls on inputs might produce fuzzy results.
840 // (Occurrences of this case suggest improvements to Value methods.)
841 //
842 // It is not possible to see Type::BOTTOM values as phi inputs,
843 // because the ciTypeFlow pre-pass produces verifier-quality types.
844 const Type* ft = t->filter(_type); // Worst case type
845
846 #ifdef ASSERT
847 // The following logic has been moved into TypeOopPtr::filter.
848 const Type* jt = t->join(_type);
849 if( jt->empty() ) { // Emptied out???
850
851 // Check for evil case of 't' being a class and '_type' expecting an
852 // interface. This can happen because the bytecodes do not contain
853 // enough type info to distinguish a Java-level interface variable
854 // from a Java-level object variable. If we meet 2 classes which
855 // both implement interface I, but their meet is at 'j/l/O' which
856 // doesn't implement I, we have no way to tell if the result should
857 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
858 // into a Phi which "knows" it's an Interface type we'll have to
859 // uplift the type.
860 if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() )
861 { assert(ft == _type, ""); } // Uplift to interface
862 // Otherwise it's something stupid like non-overlapping int ranges
863 // found on dying counted loops.
864 else
865 { assert(ft == Type::TOP, ""); } // Canonical empty value
866 }
867
868 else {
869
870 // If we have an interface-typed Phi and we narrow to a class type, the join
871 // should report back the class. However, if we have a J/L/Object
872 // class-typed Phi and an interface flows in, it's possible that the meet &
873 // join report an interface back out. This isn't possible but happens
874 // because the type system doesn't interact well with interfaces.
875 const TypeInstPtr *jtip = jt->isa_instptr();
876 if( jtip && ttip ) {
877 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
878 ttip->is_loaded() && !ttip->klass()->is_interface() )
879 // Happens in a CTW of rt.jar, 320-341, no extra flags
880 { assert(ft == ttip->cast_to_ptr_type(jtip->ptr()), ""); jt = ft; }
881 }
882 if (jt != ft && jt->base() == ft->base()) {
883 if (jt->isa_int() &&
884 jt->is_int()->_lo == ft->is_int()->_lo &&
885 jt->is_int()->_hi == ft->is_int()->_hi)
886 jt = ft;
887 if (jt->isa_long() &&
888 jt->is_long()->_lo == ft->is_long()->_lo &&
889 jt->is_long()->_hi == ft->is_long()->_hi)
890 jt = ft;
891 }
892 if (jt != ft) {
893 tty->print("merge type: "); t->dump(); tty->cr();
894 tty->print("kill type: "); _type->dump(); tty->cr();
895 tty->print("join type: "); jt->dump(); tty->cr();
896 tty->print("filter type: "); ft->dump(); tty->cr();
897 }
898 assert(jt == ft, "");
899 }
900 #endif //ASSERT
901
902 // Deal with conversion problems found in data loops.
903 ft = phase->saturate(ft, phase->type_or_null(this), _type);
904
905 return ft;
906 }
907
908
909 //------------------------------is_diamond_phi---------------------------------
910 // Does this Phi represent a simple well-shaped diamond merge? Return the
911 // index of the true path or 0 otherwise.
912 int PhiNode::is_diamond_phi() const {
913 // Check for a 2-path merge
914 Node *region = in(0);
915 if( !region ) return 0;
916 if( region->req() != 3 ) return 0;
917 if( req() != 3 ) return 0;
918 // Check that both paths come from the same If
919 Node *ifp1 = region->in(1);
920 Node *ifp2 = region->in(2);
921 if( !ifp1 || !ifp2 ) return 0;
922 Node *iff = ifp1->in(0);
923 if( !iff || !iff->is_If() ) return 0;
924 if( iff != ifp2->in(0) ) return 0;
925 // Check for a proper bool/cmp
926 const Node *b = iff->in(1);
927 if( !b->is_Bool() ) return 0;
928 const Node *cmp = b->in(1);
929 if( !cmp->is_Cmp() ) return 0;
930
931 // Check for branching opposite expected
932 if( ifp2->Opcode() == Op_IfTrue ) {
933 assert( ifp1->Opcode() == Op_IfFalse, "" );
934 return 2;
935 } else {
936 assert( ifp1->Opcode() == Op_IfTrue, "" );
937 return 1;
938 }
939 }
940
941 //----------------------------check_cmove_id-----------------------------------
942 // Check for CMove'ing a constant after comparing against the constant.
943 // Happens all the time now, since if we compare equality vs a constant in
944 // the parser, we "know" the variable is constant on one path and we force
945 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
946 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
947 // general in that we don't need constants. Since CMove's are only inserted
948 // in very special circumstances, we do it here on generic Phi's.
949 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
950 assert(true_path !=0, "only diamond shape graph expected");
951
952 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
953 // phi->region->if_proj->ifnode->bool->cmp
954 Node* region = in(0);
955 Node* iff = region->in(1)->in(0);
956 BoolNode* b = iff->in(1)->as_Bool();
957 Node* cmp = b->in(1);
958 Node* tval = in(true_path);
959 Node* fval = in(3-true_path);
960 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
961 if (id == NULL)
962 return NULL;
963
964 // Either value might be a cast that depends on a branch of 'iff'.
965 // Since the 'id' value will float free of the diamond, either
966 // decast or return failure.
967 Node* ctl = id->in(0);
968 if (ctl != NULL && ctl->in(0) == iff) {
969 if (id->is_ConstraintCast()) {
970 return id->in(1);
971 } else {
972 // Don't know how to disentangle this value.
973 return NULL;
974 }
975 }
976
977 return id;
978 }
979
980 //------------------------------Identity---------------------------------------
981 // Check for Region being Identity.
982 Node *PhiNode::Identity( PhaseTransform *phase ) {
983 // Check for no merging going on
984 // (There used to be special-case code here when this->region->is_Loop.
985 // It would check for a tributary phi on the backedge that the main phi
986 // trivially, perhaps with a single cast. The unique_input method
987 // does all this and more, by reducing such tributaries to 'this'.)
988 Node* uin = unique_input(phase);
989 if (uin != NULL) {
990 return uin;
991 }
992
993 int true_path = is_diamond_phi();
994 if (true_path != 0) {
995 Node* id = is_cmove_id(phase, true_path);
996 if (id != NULL) return id;
997 }
998
999 return this; // No identity
1000 }
1001
1002 //-----------------------------unique_input------------------------------------
1003 // Find the unique value, discounting top, self-loops, and casts.
1004 // Return top if there are no inputs, and self if there are multiple.
1005 Node* PhiNode::unique_input(PhaseTransform* phase) {
1006 // 1) One unique direct input, or
1007 // 2) some of the inputs have an intervening ConstraintCast and
1008 // the type of input is the same or sharper (more specific)
1009 // than the phi's type.
1010 // 3) an input is a self loop
1011 //
1012 // 1) input or 2) input or 3) input __
1013 // / \ / \ \ / \
1014 // \ / | cast phi cast
1015 // phi \ / / \ /
1016 // phi / --
1017
1018 Node* r = in(0); // RegionNode
1019 if (r == NULL) return in(1); // Already degraded to a Copy
1020 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
1021 Node* direct_input = NULL; // The unique direct input
1022
1023 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1024 Node* rc = r->in(i);
1025 if (rc == NULL || phase->type(rc) == Type::TOP)
1026 continue; // ignore unreachable control path
1027 Node* n = in(i);
1028 Node* un = n->uncast();
1029 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1030 continue; // ignore if top, or in(i) and "this" are in a data cycle
1031 }
1032 // Check for a unique uncasted input
1033 if (uncasted_input == NULL) {
1034 uncasted_input = un;
1035 } else if (uncasted_input != un) {
1036 uncasted_input = NodeSentinel; // no unique uncasted input
1037 }
1038 // Check for a unique direct input
1039 if (direct_input == NULL) {
1040 direct_input = n;
1041 } else if (direct_input != n) {
1042 direct_input = NodeSentinel; // no unique direct input
1043 }
1044 }
1045 if (direct_input == NULL) {
1046 return phase->C->top(); // no inputs
1047 }
1048 assert(uncasted_input != NULL,"");
1049
1050 if (direct_input != NodeSentinel) {
1051 return direct_input; // one unique direct input
1052 }
1053 if (uncasted_input != NodeSentinel &&
1054 phase->type(uncasted_input)->higher_equal(type())) {
1055 return uncasted_input; // one unique uncasted input
1056 }
1057
1058 // Nothing.
1059 return NULL;
1060 }
1061
1062 //------------------------------is_x2logic-------------------------------------
1063 // Check for simple convert-to-boolean pattern
1064 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1065 // Convert Phi to an ConvIB.
1066 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1067 assert(true_path !=0, "only diamond shape graph expected");
1068 // Convert the true/false index into an expected 0/1 return.
1069 // Map 2->0 and 1->1.
1070 int flipped = 2-true_path;
1071
1072 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1073 // phi->region->if_proj->ifnode->bool->cmp
1074 Node *region = phi->in(0);
1075 Node *iff = region->in(1)->in(0);
1076 BoolNode *b = (BoolNode*)iff->in(1);
1077 const CmpNode *cmp = (CmpNode*)b->in(1);
1078
1079 Node *zero = phi->in(1);
1080 Node *one = phi->in(2);
1081 const Type *tzero = phase->type( zero );
1082 const Type *tone = phase->type( one );
1083
1084 // Check for compare vs 0
1085 const Type *tcmp = phase->type(cmp->in(2));
1086 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1087 // Allow cmp-vs-1 if the other input is bounded by 0-1
1088 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1089 return NULL;
1090 flipped = 1-flipped; // Test is vs 1 instead of 0!
1091 }
1092
1093 // Check for setting zero/one opposite expected
1094 if( tzero == TypeInt::ZERO ) {
1095 if( tone == TypeInt::ONE ) {
1096 } else return NULL;
1097 } else if( tzero == TypeInt::ONE ) {
1098 if( tone == TypeInt::ZERO ) {
1099 flipped = 1-flipped;
1100 } else return NULL;
1101 } else return NULL;
1102
1103 // Check for boolean test backwards
1104 if( b->_test._test == BoolTest::ne ) {
1105 } else if( b->_test._test == BoolTest::eq ) {
1106 flipped = 1-flipped;
1107 } else return NULL;
1108
1109 // Build int->bool conversion
1110 Node *n = new (phase->C, 2) Conv2BNode( cmp->in(1) );
1111 if( flipped )
1112 n = new (phase->C, 3) XorINode( phase->transform(n), phase->intcon(1) );
1113
1114 return n;
1115 }
1116
1117 //------------------------------is_cond_add------------------------------------
1118 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1119 // To be profitable the control flow has to disappear; there can be no other
1120 // values merging here. We replace the test-and-branch with:
1121 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1122 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1123 // Then convert Y to 0-or-Y and finally add.
1124 // This is a key transform for SpecJava _201_compress.
1125 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1126 assert(true_path !=0, "only diamond shape graph expected");
1127
1128 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1129 // phi->region->if_proj->ifnode->bool->cmp
1130 RegionNode *region = (RegionNode*)phi->in(0);
1131 Node *iff = region->in(1)->in(0);
1132 BoolNode* b = iff->in(1)->as_Bool();
1133 const CmpNode *cmp = (CmpNode*)b->in(1);
1134
1135 // Make sure only merging this one phi here
1136 if (region->has_unique_phi() != phi) return NULL;
1137
1138 // Make sure each arm of the diamond has exactly one output, which we assume
1139 // is the region. Otherwise, the control flow won't disappear.
1140 if (region->in(1)->outcnt() != 1) return NULL;
1141 if (region->in(2)->outcnt() != 1) return NULL;
1142
1143 // Check for "(P < Q)" of type signed int
1144 if (b->_test._test != BoolTest::lt) return NULL;
1145 if (cmp->Opcode() != Op_CmpI) return NULL;
1146
1147 Node *p = cmp->in(1);
1148 Node *q = cmp->in(2);
1149 Node *n1 = phi->in( true_path);
1150 Node *n2 = phi->in(3-true_path);
1151
1152 int op = n1->Opcode();
1153 if( op != Op_AddI // Need zero as additive identity
1154 /*&&op != Op_SubI &&
1155 op != Op_AddP &&
1156 op != Op_XorI &&
1157 op != Op_OrI*/ )
1158 return NULL;
1159
1160 Node *x = n2;
1161 Node *y = n1->in(1);
1162 if( n2 == n1->in(1) ) {
1163 y = n1->in(2);
1164 } else if( n2 == n1->in(1) ) {
1165 } else return NULL;
1166
1167 // Not so profitable if compare and add are constants
1168 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1169 return NULL;
1170
1171 Node *cmplt = phase->transform( new (phase->C, 3) CmpLTMaskNode(p,q) );
1172 Node *j_and = phase->transform( new (phase->C, 3) AndINode(cmplt,y) );
1173 return new (phase->C, 3) AddINode(j_and,x);
1174 }
1175
1176 //------------------------------is_absolute------------------------------------
1177 // Check for absolute value.
1178 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1179 assert(true_path !=0, "only diamond shape graph expected");
1180
1181 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1182 int phi_x_idx = 0; // Index of phi input where to find naked x
1183
1184 // ABS ends with the merge of 2 control flow paths.
1185 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1186 int false_path = 3 - true_path;
1187
1188 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1189 // phi->region->if_proj->ifnode->bool->cmp
1190 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1191
1192 // Check bool sense
1193 switch( bol->_test._test ) {
1194 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1195 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1196 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1197 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1198 default: return NULL; break;
1199 }
1200
1201 // Test is next
1202 Node *cmp = bol->in(1);
1203 const Type *tzero = NULL;
1204 switch( cmp->Opcode() ) {
1205 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1206 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1207 default: return NULL;
1208 }
1209
1210 // Find zero input of compare; the other input is being abs'd
1211 Node *x = NULL;
1212 bool flip = false;
1213 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1214 x = cmp->in(3 - cmp_zero_idx);
1215 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1216 // The test is inverted, we should invert the result...
1217 x = cmp->in(cmp_zero_idx);
1218 flip = true;
1219 } else {
1220 return NULL;
1221 }
1222
1223 // Next get the 2 pieces being selected, one is the original value
1224 // and the other is the negated value.
1225 if( phi_root->in(phi_x_idx) != x ) return NULL;
1226
1227 // Check other phi input for subtract node
1228 Node *sub = phi_root->in(3 - phi_x_idx);
1229
1230 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1231 if( tzero == TypeF::ZERO ) {
1232 if( sub->Opcode() != Op_SubF ||
1233 sub->in(2) != x ||
1234 phase->type(sub->in(1)) != tzero ) return NULL;
1235 x = new (phase->C, 2) AbsFNode(x);
1236 if (flip) {
1237 x = new (phase->C, 3) SubFNode(sub->in(1), phase->transform(x));
1238 }
1239 } else {
1240 if( sub->Opcode() != Op_SubD ||
1241 sub->in(2) != x ||
1242 phase->type(sub->in(1)) != tzero ) return NULL;
1243 x = new (phase->C, 2) AbsDNode(x);
1244 if (flip) {
1245 x = new (phase->C, 3) SubDNode(sub->in(1), phase->transform(x));
1246 }
1247 }
1248
1249 return x;
1250 }
1251
1252 //------------------------------split_once-------------------------------------
1253 // Helper for split_flow_path
1254 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1255 igvn->hash_delete(n); // Remove from hash before hacking edges
1256
1257 uint j = 1;
1258 for( uint i = phi->req()-1; i > 0; i-- ) {
1259 if( phi->in(i) == val ) { // Found a path with val?
1260 // Add to NEW Region/Phi, no DU info
1261 newn->set_req( j++, n->in(i) );
1262 // Remove from OLD Region/Phi
1263 n->del_req(i);
1264 }
1265 }
1266
1267 // Register the new node but do not transform it. Cannot transform until the
1268 // entire Region/Phi conglerate has been hacked as a single huge transform.
1269 igvn->register_new_node_with_optimizer( newn );
1270 // Now I can point to the new node.
1271 n->add_req(newn);
1272 igvn->_worklist.push(n);
1273 }
1274
1275 //------------------------------split_flow_path--------------------------------
1276 // Check for merging identical values and split flow paths
1277 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1278 BasicType bt = phi->type()->basic_type();
1279 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1280 return NULL; // Bail out on funny non-value stuff
1281 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1282 return NULL; // third unequal input to be worth doing
1283
1284 // Scan for a constant
1285 uint i;
1286 for( i = 1; i < phi->req()-1; i++ ) {
1287 Node *n = phi->in(i);
1288 if( !n ) return NULL;
1289 if( phase->type(n) == Type::TOP ) return NULL;
1290 if( n->Opcode() == Op_ConP )
1291 break;
1292 }
1293 if( i >= phi->req() ) // Only split for constants
1294 return NULL;
1295
1296 Node *val = phi->in(i); // Constant to split for
1297 uint hit = 0; // Number of times it occurs
1298
1299 for( ; i < phi->req(); i++ ){ // Count occurances of constant
1300 Node *n = phi->in(i);
1301 if( !n ) return NULL;
1302 if( phase->type(n) == Type::TOP ) return NULL;
1303 if( phi->in(i) == val )
1304 hit++;
1305 }
1306
1307 if( hit <= 1 || // Make sure we find 2 or more
1308 hit == phi->req()-1 ) // and not ALL the same value
1309 return NULL;
1310
1311 // Now start splitting out the flow paths that merge the same value.
1312 // Split first the RegionNode.
1313 PhaseIterGVN *igvn = phase->is_IterGVN();
1314 Node *r = phi->region();
1315 RegionNode *newr = new (phase->C, hit+1) RegionNode(hit+1);
1316 split_once(igvn, phi, val, r, newr);
1317
1318 // Now split all other Phis than this one
1319 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1320 Node* phi2 = r->fast_out(k);
1321 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1322 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1323 split_once(igvn, phi, val, phi2, newphi);
1324 }
1325 }
1326
1327 // Clean up this guy
1328 igvn->hash_delete(phi);
1329 for( i = phi->req()-1; i > 0; i-- ) {
1330 if( phi->in(i) == val ) {
1331 phi->del_req(i);
1332 }
1333 }
1334 phi->add_req(val);
1335
1336 return phi;
1337 }
1338
1339 //=============================================================================
1340 //------------------------------simple_data_loop_check-------------------------
1341 // Try to determing if the phi node in a simple safe/unsafe data loop.
1342 // Returns:
1343 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1344 // Safe - safe case when the phi and it's inputs reference only safe data
1345 // nodes;
1346 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1347 // is no reference back to the phi - need a graph walk
1348 // to determine if it is in a loop;
1349 // UnsafeLoop - unsafe case when the phi references itself directly or through
1350 // unsafe data node.
1351 // Note: a safe data node is a node which could/never reference itself during
1352 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1353 // I mark Phi nodes as safe node not only because they can reference itself
1354 // but also to prevent mistaking the fallthrough case inside an outer loop
1355 // as dead loop when the phi references itselfs through an other phi.
1356 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1357 // It is unsafe loop if the phi node references itself directly.
1358 if (in == (Node*)this)
1359 return UnsafeLoop; // Unsafe loop
1360 // Unsafe loop if the phi node references itself through an unsafe data node.
1361 // Exclude cases with null inputs or data nodes which could reference
1362 // itself (safe for dead loops).
1363 if (in != NULL && !in->is_dead_loop_safe()) {
1364 // Check inputs of phi's inputs also.
1365 // It is much less expensive then full graph walk.
1366 uint cnt = in->req();
1367 for (uint i = 1; i < cnt; ++i) {
1368 Node* m = in->in(i);
1369 if (m == (Node*)this)
1370 return UnsafeLoop; // Unsafe loop
1371 if (m != NULL && !m->is_dead_loop_safe()) {
1372 // Check the most common case (about 30% of all cases):
1373 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1374 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1375 if (m1 == (Node*)this)
1376 return UnsafeLoop; // Unsafe loop
1377 if (m1 != NULL && m1 == m->in(2) &&
1378 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1379 continue; // Safe case
1380 }
1381 // The phi references an unsafe node - need full analysis.
1382 return Unsafe;
1383 }
1384 }
1385 }
1386 return Safe; // Safe case - we can optimize the phi node.
1387 }
1388
1389 //------------------------------is_unsafe_data_reference-----------------------
1390 // If phi can be reached through the data input - it is data loop.
1391 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1392 assert(req() > 1, "");
1393 // First, check simple cases when phi references itself directly or
1394 // through an other node.
1395 LoopSafety safety = simple_data_loop_check(in);
1396 if (safety == UnsafeLoop)
1397 return true; // phi references itself - unsafe loop
1398 else if (safety == Safe)
1399 return false; // Safe case - phi could be replaced with the unique input.
1400
1401 // Unsafe case when we should go through data graph to determine
1402 // if the phi references itself.
1403
1404 ResourceMark rm;
1405
1406 Arena *a = Thread::current()->resource_area();
1407 Node_List nstack(a);
1408 VectorSet visited(a);
1409
1410 nstack.push(in); // Start with unique input.
1411 visited.set(in->_idx);
1412 while (nstack.size() != 0) {
1413 Node* n = nstack.pop();
1414 uint cnt = n->req();
1415 for (uint i = 1; i < cnt; i++) { // Only data paths
1416 Node* m = n->in(i);
1417 if (m == (Node*)this) {
1418 return true; // Data loop
1419 }
1420 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1421 if (!visited.test_set(m->_idx))
1422 nstack.push(m);
1423 }
1424 }
1425 }
1426 return false; // The phi is not reachable from its inputs
1427 }
1428
1429
1430 //------------------------------Ideal------------------------------------------
1431 // Return a node which is more "ideal" than the current node. Must preserve
1432 // the CFG, but we can still strip out dead paths.
1433 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1434 // The next should never happen after 6297035 fix.
1435 if( is_copy() ) // Already degraded to a Copy ?
1436 return NULL; // No change
1437
1438 Node *r = in(0); // RegionNode
1439 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1440
1441 // Note: During parsing, phis are often transformed before their regions.
1442 // This means we have to use type_or_null to defend against untyped regions.
1443 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1444 return NULL; // No change
1445
1446 Node *top = phase->C->top();
1447
1448 // The are 2 situations when only one valid phi's input is left
1449 // (in addition to Region input).
1450 // One: region is not loop - replace phi with this input.
1451 // Two: region is loop - replace phi with top since this data path is dead
1452 // and we need to break the dead data loop.
1453 Node* progress = NULL; // Record if any progress made
1454 for( uint j = 1; j < req(); ++j ){ // For all paths in
1455 // Check unreachable control paths
1456 Node* rc = r->in(j);
1457 Node* n = in(j); // Get the input
1458 if (rc == NULL || phase->type(rc) == Type::TOP) {
1459 if (n != top) { // Not already top?
1460 set_req(j, top); // Nuke it down
1461 progress = this; // Record progress
1462 }
1463 }
1464 }
1465
1466 Node* uin = unique_input(phase);
1467 if (uin == top) { // Simplest case: no alive inputs.
1468 if (can_reshape) // IGVN transformation
1469 return top;
1470 else
1471 return NULL; // Identity will return TOP
1472 } else if (uin != NULL) {
1473 // Only one not-NULL unique input path is left.
1474 // Determine if this input is backedge of a loop.
1475 // (Skip new phis which have no uses and dead regions).
1476 if( outcnt() > 0 && r->in(0) != NULL ) {
1477 // First, take the short cut when we know it is a loop and
1478 // the EntryControl data path is dead.
1479 assert(!r->is_Loop() || r->req() == 3, "Loop node should have 3 inputs");
1480 // Then, check if there is a data loop when phi references itself directly
1481 // or through other data nodes.
1482 if( r->is_Loop() && !phase->eqv_uncast(uin, in(LoopNode::EntryControl)) ||
1483 !r->is_Loop() && is_unsafe_data_reference(uin) ) {
1484 // Break this data loop to avoid creation of a dead loop.
1485 if (can_reshape) {
1486 return top;
1487 } else {
1488 // We can't return top if we are in Parse phase - cut inputs only
1489 // let Identity to handle the case.
1490 replace_edge(uin, top);
1491 return NULL;
1492 }
1493 }
1494 }
1495
1496 // One unique input.
1497 debug_only(Node* ident = Identity(phase));
1498 // The unique input must eventually be detected by the Identity call.
1499 #ifdef ASSERT
1500 if (ident != uin && !ident->is_top()) {
1501 // print this output before failing assert
1502 r->dump(3);
1503 this->dump(3);
1504 ident->dump();
1505 uin->dump();
1506 }
1507 #endif
1508 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1509 return NULL;
1510 }
1511
1512
1513 Node* opt = NULL;
1514 int true_path = is_diamond_phi();
1515 if( true_path != 0 ) {
1516 // Check for CMove'ing identity. If it would be unsafe,
1517 // handle it here. In the safe case, let Identity handle it.
1518 Node* unsafe_id = is_cmove_id(phase, true_path);
1519 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1520 opt = unsafe_id;
1521
1522 // Check for simple convert-to-boolean pattern
1523 if( opt == NULL )
1524 opt = is_x2logic(phase, this, true_path);
1525
1526 // Check for absolute value
1527 if( opt == NULL )
1528 opt = is_absolute(phase, this, true_path);
1529
1530 // Check for conditional add
1531 if( opt == NULL && can_reshape )
1532 opt = is_cond_add(phase, this, true_path);
1533
1534 // These 4 optimizations could subsume the phi:
1535 // have to check for a dead data loop creation.
1536 if( opt != NULL ) {
1537 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1538 // Found dead loop.
1539 if( can_reshape )
1540 return top;
1541 // We can't return top if we are in Parse phase - cut inputs only
1542 // to stop further optimizations for this phi. Identity will return TOP.
1543 assert(req() == 3, "only diamond merge phi here");
1544 set_req(1, top);
1545 set_req(2, top);
1546 return NULL;
1547 } else {
1548 return opt;
1549 }
1550 }
1551 }
1552
1553 // Check for merging identical values and split flow paths
1554 if (can_reshape) {
1555 opt = split_flow_path(phase, this);
1556 // This optimization only modifies phi - don't need to check for dead loop.
1557 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1558 if (opt != NULL) return opt;
1559 }
1560
1561 // Split phis through memory merges, so that the memory merges will go away.
1562 // Piggy-back this transformation on the search for a unique input....
1563 // It will be as if the merged memory is the unique value of the phi.
1564 // (Do not attempt this optimization unless parsing is complete.
1565 // It would make the parser's memory-merge logic sick.)
1566 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1567 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1568 // see if this phi should be sliced
1569 uint merge_width = 0;
1570 bool saw_self = false;
1571 for( uint i=1; i<req(); ++i ) {// For all paths in
1572 Node *ii = in(i);
1573 if (ii->is_MergeMem()) {
1574 MergeMemNode* n = ii->as_MergeMem();
1575 merge_width = MAX2(merge_width, n->req());
1576 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1577 }
1578 }
1579
1580 // This restriction is temporarily necessary to ensure termination:
1581 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1582
1583 if (merge_width > Compile::AliasIdxRaw) {
1584 // found at least one non-empty MergeMem
1585 const TypePtr* at = adr_type();
1586 if (at != TypePtr::BOTTOM) {
1587 // Patch the existing phi to select an input from the merge:
1588 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1589 // Phi:AT1(...m1...)
1590 int alias_idx = phase->C->get_alias_index(at);
1591 for (uint i=1; i<req(); ++i) {
1592 Node *ii = in(i);
1593 if (ii->is_MergeMem()) {
1594 MergeMemNode* n = ii->as_MergeMem();
1595 // compress paths and change unreachable cycles to TOP
1596 // If not, we can update the input infinitely along a MergeMem cycle
1597 // Equivalent code is in MemNode::Ideal_common
1598 Node *m = phase->transform(n);
1599 // If tranformed to a MergeMem, get the desired slice
1600 // Otherwise the returned node represents memory for every slice
1601 Node *new_mem = (m->is_MergeMem()) ?
1602 m->as_MergeMem()->memory_at(alias_idx) : m;
1603 // Update input if it is progress over what we have now
1604 if (new_mem != ii) {
1605 set_req(i, new_mem);
1606 progress = this;
1607 }
1608 }
1609 }
1610 } else {
1611 // We know that at least one MergeMem->base_memory() == this
1612 // (saw_self == true). If all other inputs also references this phi
1613 // (directly or through data nodes) - it is dead loop.
1614 bool saw_safe_input = false;
1615 for (uint j = 1; j < req(); ++j) {
1616 Node *n = in(j);
1617 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1618 continue; // skip known cases
1619 if (!is_unsafe_data_reference(n)) {
1620 saw_safe_input = true; // found safe input
1621 break;
1622 }
1623 }
1624 if (!saw_safe_input)
1625 return top; // all inputs reference back to this phi - dead loop
1626
1627 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1628 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1629 PhaseIterGVN *igvn = phase->is_IterGVN();
1630 Node* hook = new (phase->C, 1) Node(1);
1631 PhiNode* new_base = (PhiNode*) clone();
1632 // Must eagerly register phis, since they participate in loops.
1633 if (igvn) {
1634 igvn->register_new_node_with_optimizer(new_base);
1635 hook->add_req(new_base);
1636 }
1637 MergeMemNode* result = MergeMemNode::make(phase->C, new_base);
1638 for (uint i = 1; i < req(); ++i) {
1639 Node *ii = in(i);
1640 if (ii->is_MergeMem()) {
1641 MergeMemNode* n = ii->as_MergeMem();
1642 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1643 // If we have not seen this slice yet, make a phi for it.
1644 bool made_new_phi = false;
1645 if (mms.is_empty()) {
1646 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1647 made_new_phi = true;
1648 if (igvn) {
1649 igvn->register_new_node_with_optimizer(new_phi);
1650 hook->add_req(new_phi);
1651 }
1652 mms.set_memory(new_phi);
1653 }
1654 Node* phi = mms.memory();
1655 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1656 phi->set_req(i, mms.memory2());
1657 }
1658 }
1659 }
1660 // Distribute all self-loops.
1661 { // (Extra braces to hide mms.)
1662 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1663 Node* phi = mms.memory();
1664 for (uint i = 1; i < req(); ++i) {
1665 if (phi->in(i) == this) phi->set_req(i, phi);
1666 }
1667 }
1668 }
1669 // now transform the new nodes, and return the mergemem
1670 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1671 Node* phi = mms.memory();
1672 mms.set_memory(phase->transform(phi));
1673 }
1674 if (igvn) { // Unhook.
1675 igvn->hash_delete(hook);
1676 for (uint i = 1; i < hook->req(); i++) {
1677 hook->set_req(i, NULL);
1678 }
1679 }
1680 // Replace self with the result.
1681 return result;
1682 }
1683 }
1684 }
1685
1686 return progress; // Return any progress
1687 }
1688
1689 //------------------------------out_RegMask------------------------------------
1690 const RegMask &PhiNode::in_RegMask(uint i) const {
1691 return i ? out_RegMask() : RegMask::Empty;
1692 }
1693
1694 const RegMask &PhiNode::out_RegMask() const {
1695 uint ideal_reg = Matcher::base2reg[_type->base()];
1696 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
1697 if( ideal_reg == 0 ) return RegMask::Empty;
1698 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
1699 }
1700
1701 #ifndef PRODUCT
1702 void PhiNode::dump_spec(outputStream *st) const {
1703 TypeNode::dump_spec(st);
1704 if (in(0) != NULL &&
1705 in(0)->is_CountedLoop() &&
1706 in(0)->as_CountedLoop()->phi() == this) {
1707 st->print(" #tripcount");
1708 }
1709 }
1710 #endif
1711
1712
1713 //=============================================================================
1714 const Type *GotoNode::Value( PhaseTransform *phase ) const {
1715 // If the input is reachable, then we are executed.
1716 // If the input is not reachable, then we are not executed.
1717 return phase->type(in(0));
1718 }
1719
1720 Node *GotoNode::Identity( PhaseTransform *phase ) {
1721 return in(0); // Simple copy of incoming control
1722 }
1723
1724 const RegMask &GotoNode::out_RegMask() const {
1725 return RegMask::Empty;
1726 }
1727
1728 //=============================================================================
1729 const RegMask &JumpNode::out_RegMask() const {
1730 return RegMask::Empty;
1731 }
1732
1733 //=============================================================================
1734 const RegMask &JProjNode::out_RegMask() const {
1735 return RegMask::Empty;
1736 }
1737
1738 //=============================================================================
1739 const RegMask &CProjNode::out_RegMask() const {
1740 return RegMask::Empty;
1741 }
1742
1743
1744
1745 //=============================================================================
1746
1747 uint PCTableNode::hash() const { return Node::hash() + _size; }
1748 uint PCTableNode::cmp( const Node &n ) const
1749 { return _size == ((PCTableNode&)n)._size; }
1750
1751 const Type *PCTableNode::bottom_type() const {
1752 const Type** f = TypeTuple::fields(_size);
1753 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
1754 return TypeTuple::make(_size, f);
1755 }
1756
1757 //------------------------------Value------------------------------------------
1758 // Compute the type of the PCTableNode. If reachable it is a tuple of
1759 // Control, otherwise the table targets are not reachable
1760 const Type *PCTableNode::Value( PhaseTransform *phase ) const {
1761 if( phase->type(in(0)) == Type::CONTROL )
1762 return bottom_type();
1763 return Type::TOP; // All paths dead? Then so are we
1764 }
1765
1766 //------------------------------Ideal------------------------------------------
1767 // Return a node which is more "ideal" than the current node. Strip out
1768 // control copies
1769 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1770 return remove_dead_region(phase, can_reshape) ? this : NULL;
1771 }
1772
1773 //=============================================================================
1774 uint JumpProjNode::hash() const {
1775 return Node::hash() + _dest_bci;
1776 }
1777
1778 uint JumpProjNode::cmp( const Node &n ) const {
1779 return ProjNode::cmp(n) &&
1780 _dest_bci == ((JumpProjNode&)n)._dest_bci;
1781 }
1782
1783 #ifndef PRODUCT
1784 void JumpProjNode::dump_spec(outputStream *st) const {
1785 ProjNode::dump_spec(st);
1786 st->print("@bci %d ",_dest_bci);
1787 }
1788 #endif
1789
1790 //=============================================================================
1791 //------------------------------Value------------------------------------------
1792 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
1793 // have the default "fall_through_index" path.
1794 const Type *CatchNode::Value( PhaseTransform *phase ) const {
1795 // Unreachable? Then so are all paths from here.
1796 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
1797 // First assume all paths are reachable
1798 const Type** f = TypeTuple::fields(_size);
1799 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
1800 // Identify cases that will always throw an exception
1801 // () rethrow call
1802 // () virtual or interface call with NULL receiver
1803 // () call is a check cast with incompatible arguments
1804 if( in(1)->is_Proj() ) {
1805 Node *i10 = in(1)->in(0);
1806 if( i10->is_Call() ) {
1807 CallNode *call = i10->as_Call();
1808 // Rethrows always throw exceptions, never return
1809 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
1810 f[CatchProjNode::fall_through_index] = Type::TOP;
1811 } else if( call->req() > TypeFunc::Parms ) {
1812 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
1813 // Check for null reciever to virtual or interface calls
1814 if( call->is_CallDynamicJava() &&
1815 arg0->higher_equal(TypePtr::NULL_PTR) ) {
1816 f[CatchProjNode::fall_through_index] = Type::TOP;
1817 }
1818 } // End of if not a runtime stub
1819 } // End of if have call above me
1820 } // End of slot 1 is not a projection
1821 return TypeTuple::make(_size, f);
1822 }
1823
1824 //=============================================================================
1825 uint CatchProjNode::hash() const {
1826 return Node::hash() + _handler_bci;
1827 }
1828
1829
1830 uint CatchProjNode::cmp( const Node &n ) const {
1831 return ProjNode::cmp(n) &&
1832 _handler_bci == ((CatchProjNode&)n)._handler_bci;
1833 }
1834
1835
1836 //------------------------------Identity---------------------------------------
1837 // If only 1 target is possible, choose it if it is the main control
1838 Node *CatchProjNode::Identity( PhaseTransform *phase ) {
1839 // If my value is control and no other value is, then treat as ID
1840 const TypeTuple *t = phase->type(in(0))->is_tuple();
1841 if (t->field_at(_con) != Type::CONTROL) return this;
1842 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
1843 // also remove any exception table entry. Thus we must know the call
1844 // feeding the Catch will not really throw an exception. This is ok for
1845 // the main fall-thru control (happens when we know a call can never throw
1846 // an exception) or for "rethrow", because a further optimnization will
1847 // yank the rethrow (happens when we inline a function that can throw an
1848 // exception and the caller has no handler). Not legal, e.g., for passing
1849 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
1850 // These cases MUST throw an exception via the runtime system, so the VM
1851 // will be looking for a table entry.
1852 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
1853 CallNode *call;
1854 if (_con != TypeFunc::Control && // Bail out if not the main control.
1855 !(proj->is_Proj() && // AND NOT a rethrow
1856 proj->in(0)->is_Call() &&
1857 (call = proj->in(0)->as_Call()) &&
1858 call->entry_point() == OptoRuntime::rethrow_stub()))
1859 return this;
1860
1861 // Search for any other path being control
1862 for (uint i = 0; i < t->cnt(); i++) {
1863 if (i != _con && t->field_at(i) == Type::CONTROL)
1864 return this;
1865 }
1866 // Only my path is possible; I am identity on control to the jump
1867 return in(0)->in(0);
1868 }
1869
1870
1871 #ifndef PRODUCT
1872 void CatchProjNode::dump_spec(outputStream *st) const {
1873 ProjNode::dump_spec(st);
1874 st->print("@bci %d ",_handler_bci);
1875 }
1876 #endif
1877
1878 //=============================================================================
1879 //------------------------------Identity---------------------------------------
1880 // Check for CreateEx being Identity.
1881 Node *CreateExNode::Identity( PhaseTransform *phase ) {
1882 if( phase->type(in(1)) == Type::TOP ) return in(1);
1883 if( phase->type(in(0)) == Type::TOP ) return in(0);
1884 // We only come from CatchProj, unless the CatchProj goes away.
1885 // If the CatchProj is optimized away, then we just carry the
1886 // exception oop through.
1887 CallNode *call = in(1)->in(0)->as_Call();
1888
1889 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
1890 ? this
1891 : call->in(TypeFunc::Parms);
1892 }
1893
1894 //=============================================================================
1895 #ifndef PRODUCT
1896 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
1897 st->print("%s", Name());
1898 }
1899 #endif
1900