Wed, 13 Apr 2011 14:33:03 -0700
6988308: assert((cnt > 0.0f) && (prob > 0.0f)) failed: Bad frequency assignment in if
Summary: Make sure cnt doesn't become negative and integer overflow doesn't happen.
Reviewed-by: kvn, twisti
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "oops/objArrayKlass.hpp"
29 #include "opto/addnode.hpp"
30 #include "opto/cfgnode.hpp"
31 #include "opto/connode.hpp"
32 #include "opto/loopnode.hpp"
33 #include "opto/machnode.hpp"
34 #include "opto/mulnode.hpp"
35 #include "opto/phaseX.hpp"
36 #include "opto/regmask.hpp"
37 #include "opto/runtime.hpp"
38 #include "opto/subnode.hpp"
40 // Portions of code courtesy of Clifford Click
42 // Optimization - Graph Style
44 //=============================================================================
45 //------------------------------Value------------------------------------------
46 // Compute the type of the RegionNode.
47 const Type *RegionNode::Value( PhaseTransform *phase ) const {
48 for( uint i=1; i<req(); ++i ) { // For all paths in
49 Node *n = in(i); // Get Control source
50 if( !n ) continue; // Missing inputs are TOP
51 if( phase->type(n) == Type::CONTROL )
52 return Type::CONTROL;
53 }
54 return Type::TOP; // All paths dead? Then so are we
55 }
57 //------------------------------Identity---------------------------------------
58 // Check for Region being Identity.
59 Node *RegionNode::Identity( PhaseTransform *phase ) {
60 // Cannot have Region be an identity, even if it has only 1 input.
61 // Phi users cannot have their Region input folded away for them,
62 // since they need to select the proper data input
63 return this;
64 }
66 //------------------------------merge_region-----------------------------------
67 // If a Region flows into a Region, merge into one big happy merge. This is
68 // hard to do if there is stuff that has to happen
69 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
70 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
71 return NULL;
72 Node *progress = NULL; // Progress flag
73 PhaseIterGVN *igvn = phase->is_IterGVN();
75 uint rreq = region->req();
76 for( uint i = 1; i < rreq; i++ ) {
77 Node *r = region->in(i);
78 if( r && r->Opcode() == Op_Region && // Found a region?
79 r->in(0) == r && // Not already collapsed?
80 r != region && // Avoid stupid situations
81 r->outcnt() == 2 ) { // Self user and 'region' user only?
82 assert(!r->as_Region()->has_phi(), "no phi users");
83 if( !progress ) { // No progress
84 if (region->has_phi()) {
85 return NULL; // Only flatten if no Phi users
86 // igvn->hash_delete( phi );
87 }
88 igvn->hash_delete( region );
89 progress = region; // Making progress
90 }
91 igvn->hash_delete( r );
93 // Append inputs to 'r' onto 'region'
94 for( uint j = 1; j < r->req(); j++ ) {
95 // Move an input from 'r' to 'region'
96 region->add_req(r->in(j));
97 r->set_req(j, phase->C->top());
98 // Update phis of 'region'
99 //for( uint k = 0; k < max; k++ ) {
100 // Node *phi = region->out(k);
101 // if( phi->is_Phi() ) {
102 // phi->add_req(phi->in(i));
103 // }
104 //}
106 rreq++; // One more input to Region
107 } // Found a region to merge into Region
108 // Clobber pointer to the now dead 'r'
109 region->set_req(i, phase->C->top());
110 }
111 }
113 return progress;
114 }
118 //--------------------------------has_phi--------------------------------------
119 // Helper function: Return any PhiNode that uses this region or NULL
120 PhiNode* RegionNode::has_phi() const {
121 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
122 Node* phi = fast_out(i);
123 if (phi->is_Phi()) { // Check for Phi users
124 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
125 return phi->as_Phi(); // this one is good enough
126 }
127 }
129 return NULL;
130 }
133 //-----------------------------has_unique_phi----------------------------------
134 // Helper function: Return the only PhiNode that uses this region or NULL
135 PhiNode* RegionNode::has_unique_phi() const {
136 // Check that only one use is a Phi
137 PhiNode* only_phi = NULL;
138 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
139 Node* phi = fast_out(i);
140 if (phi->is_Phi()) { // Check for Phi users
141 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
142 if (only_phi == NULL) {
143 only_phi = phi->as_Phi();
144 } else {
145 return NULL; // multiple phis
146 }
147 }
148 }
150 return only_phi;
151 }
154 //------------------------------check_phi_clipping-----------------------------
155 // Helper function for RegionNode's identification of FP clipping
156 // Check inputs to the Phi
157 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
158 min = NULL;
159 max = NULL;
160 val = NULL;
161 min_idx = 0;
162 max_idx = 0;
163 val_idx = 0;
164 uint phi_max = phi->req();
165 if( phi_max == 4 ) {
166 for( uint j = 1; j < phi_max; ++j ) {
167 Node *n = phi->in(j);
168 int opcode = n->Opcode();
169 switch( opcode ) {
170 case Op_ConI:
171 {
172 if( min == NULL ) {
173 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
174 min_idx = j;
175 } else {
176 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
177 max_idx = j;
178 if( min->get_int() > max->get_int() ) {
179 // Swap min and max
180 ConNode *temp;
181 uint temp_idx;
182 temp = min; min = max; max = temp;
183 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
184 }
185 }
186 }
187 break;
188 default:
189 {
190 val = n;
191 val_idx = j;
192 }
193 break;
194 }
195 }
196 }
197 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
198 }
201 //------------------------------check_if_clipping------------------------------
202 // Helper function for RegionNode's identification of FP clipping
203 // Check that inputs to Region come from two IfNodes,
204 //
205 // If
206 // False True
207 // If |
208 // False True |
209 // | | |
210 // RegionNode_inputs
211 //
212 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
213 top_if = NULL;
214 bot_if = NULL;
216 // Check control structure above RegionNode for (if ( if ) )
217 Node *in1 = region->in(1);
218 Node *in2 = region->in(2);
219 Node *in3 = region->in(3);
220 // Check that all inputs are projections
221 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
222 Node *in10 = in1->in(0);
223 Node *in20 = in2->in(0);
224 Node *in30 = in3->in(0);
225 // Check that #1 and #2 are ifTrue and ifFalse from same If
226 if( in10 != NULL && in10->is_If() &&
227 in20 != NULL && in20->is_If() &&
228 in30 != NULL && in30->is_If() && in10 == in20 &&
229 (in1->Opcode() != in2->Opcode()) ) {
230 Node *in100 = in10->in(0);
231 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
232 // Check that control for in10 comes from other branch of IF from in3
233 if( in1000 != NULL && in1000->is_If() &&
234 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
235 // Control pattern checks
236 top_if = (IfNode*)in1000;
237 bot_if = (IfNode*)in10;
238 }
239 }
240 }
242 return (top_if != NULL);
243 }
246 //------------------------------check_convf2i_clipping-------------------------
247 // Helper function for RegionNode's identification of FP clipping
248 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
249 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
250 convf2i = NULL;
252 // Check for the RShiftNode
253 Node *rshift = phi->in(idx);
254 assert( rshift, "Previous checks ensure phi input is present");
255 if( rshift->Opcode() != Op_RShiftI ) { return false; }
257 // Check for the LShiftNode
258 Node *lshift = rshift->in(1);
259 assert( lshift, "Previous checks ensure phi input is present");
260 if( lshift->Opcode() != Op_LShiftI ) { return false; }
262 // Check for the ConvF2INode
263 Node *conv = lshift->in(1);
264 if( conv->Opcode() != Op_ConvF2I ) { return false; }
266 // Check that shift amounts are only to get sign bits set after F2I
267 jint max_cutoff = max->get_int();
268 jint min_cutoff = min->get_int();
269 jint left_shift = lshift->in(2)->get_int();
270 jint right_shift = rshift->in(2)->get_int();
271 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
272 if( left_shift != right_shift ||
273 0 > left_shift || left_shift >= BitsPerJavaInteger ||
274 max_post_shift < max_cutoff ||
275 max_post_shift < -min_cutoff ) {
276 // Shifts are necessary but current transformation eliminates them
277 return false;
278 }
280 // OK to return the result of ConvF2I without shifting
281 convf2i = (ConvF2INode*)conv;
282 return true;
283 }
286 //------------------------------check_compare_clipping-------------------------
287 // Helper function for RegionNode's identification of FP clipping
288 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
289 Node *i1 = iff->in(1);
290 if ( !i1->is_Bool() ) { return false; }
291 BoolNode *bool1 = i1->as_Bool();
292 if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
293 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
294 const Node *cmpF = bool1->in(1);
295 if( cmpF->Opcode() != Op_CmpF ) { return false; }
296 // Test that the float value being compared against
297 // is equivalent to the int value used as a limit
298 Node *nodef = cmpF->in(2);
299 if( nodef->Opcode() != Op_ConF ) { return false; }
300 jfloat conf = nodef->getf();
301 jint coni = limit->get_int();
302 if( ((int)conf) != coni ) { return false; }
303 input = cmpF->in(1);
304 return true;
305 }
307 //------------------------------is_unreachable_region--------------------------
308 // Find if the Region node is reachable from the root.
309 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
310 assert(req() == 2, "");
312 // First, cut the simple case of fallthrough region when NONE of
313 // region's phis references itself directly or through a data node.
314 uint max = outcnt();
315 uint i;
316 for (i = 0; i < max; i++) {
317 Node* phi = raw_out(i);
318 if (phi != NULL && phi->is_Phi()) {
319 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
320 if (phi->outcnt() == 0)
321 continue; // Safe case - no loops
322 if (phi->outcnt() == 1) {
323 Node* u = phi->raw_out(0);
324 // Skip if only one use is an other Phi or Call or Uncommon trap.
325 // It is safe to consider this case as fallthrough.
326 if (u != NULL && (u->is_Phi() || u->is_CFG()))
327 continue;
328 }
329 // Check when phi references itself directly or through an other node.
330 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
331 break; // Found possible unsafe data loop.
332 }
333 }
334 if (i >= max)
335 return false; // An unsafe case was NOT found - don't need graph walk.
337 // Unsafe case - check if the Region node is reachable from root.
338 ResourceMark rm;
340 Arena *a = Thread::current()->resource_area();
341 Node_List nstack(a);
342 VectorSet visited(a);
344 // Mark all control nodes reachable from root outputs
345 Node *n = (Node*)phase->C->root();
346 nstack.push(n);
347 visited.set(n->_idx);
348 while (nstack.size() != 0) {
349 n = nstack.pop();
350 uint max = n->outcnt();
351 for (uint i = 0; i < max; i++) {
352 Node* m = n->raw_out(i);
353 if (m != NULL && m->is_CFG()) {
354 if (phase->eqv(m, this)) {
355 return false; // We reached the Region node - it is not dead.
356 }
357 if (!visited.test_set(m->_idx))
358 nstack.push(m);
359 }
360 }
361 }
363 return true; // The Region node is unreachable - it is dead.
364 }
366 //------------------------------Ideal------------------------------------------
367 // Return a node which is more "ideal" than the current node. Must preserve
368 // the CFG, but we can still strip out dead paths.
369 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
370 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
371 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
373 // Check for RegionNode with no Phi users and both inputs come from either
374 // arm of the same IF. If found, then the control-flow split is useless.
375 bool has_phis = false;
376 if (can_reshape) { // Need DU info to check for Phi users
377 has_phis = (has_phi() != NULL); // Cache result
378 if (!has_phis) { // No Phi users? Nothing merging?
379 for (uint i = 1; i < req()-1; i++) {
380 Node *if1 = in(i);
381 if( !if1 ) continue;
382 Node *iff = if1->in(0);
383 if( !iff || !iff->is_If() ) continue;
384 for( uint j=i+1; j<req(); j++ ) {
385 if( in(j) && in(j)->in(0) == iff &&
386 if1->Opcode() != in(j)->Opcode() ) {
387 // Add the IF Projections to the worklist. They (and the IF itself)
388 // will be eliminated if dead.
389 phase->is_IterGVN()->add_users_to_worklist(iff);
390 set_req(i, iff->in(0));// Skip around the useless IF diamond
391 set_req(j, NULL);
392 return this; // Record progress
393 }
394 }
395 }
396 }
397 }
399 // Remove TOP or NULL input paths. If only 1 input path remains, this Region
400 // degrades to a copy.
401 bool add_to_worklist = false;
402 int cnt = 0; // Count of values merging
403 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
404 int del_it = 0; // The last input path we delete
405 // For all inputs...
406 for( uint i=1; i<req(); ++i ){// For all paths in
407 Node *n = in(i); // Get the input
408 if( n != NULL ) {
409 // Remove useless control copy inputs
410 if( n->is_Region() && n->as_Region()->is_copy() ) {
411 set_req(i, n->nonnull_req());
412 i--;
413 continue;
414 }
415 if( n->is_Proj() ) { // Remove useless rethrows
416 Node *call = n->in(0);
417 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
418 set_req(i, call->in(0));
419 i--;
420 continue;
421 }
422 }
423 if( phase->type(n) == Type::TOP ) {
424 set_req(i, NULL); // Ignore TOP inputs
425 i--;
426 continue;
427 }
428 cnt++; // One more value merging
430 } else if (can_reshape) { // Else found dead path with DU info
431 PhaseIterGVN *igvn = phase->is_IterGVN();
432 del_req(i); // Yank path from self
433 del_it = i;
434 uint max = outcnt();
435 DUIterator j;
436 bool progress = true;
437 while(progress) { // Need to establish property over all users
438 progress = false;
439 for (j = outs(); has_out(j); j++) {
440 Node *n = out(j);
441 if( n->req() != req() && n->is_Phi() ) {
442 assert( n->in(0) == this, "" );
443 igvn->hash_delete(n); // Yank from hash before hacking edges
444 n->set_req_X(i,NULL,igvn);// Correct DU info
445 n->del_req(i); // Yank path from Phis
446 if( max != outcnt() ) {
447 progress = true;
448 j = refresh_out_pos(j);
449 max = outcnt();
450 }
451 }
452 }
453 }
454 add_to_worklist = true;
455 i--;
456 }
457 }
459 if (can_reshape && cnt == 1) {
460 // Is it dead loop?
461 // If it is LoopNopde it had 2 (+1 itself) inputs and
462 // one of them was cut. The loop is dead if it was EntryContol.
463 assert(!this->is_Loop() || cnt_orig == 3, "Loop node should have 3 inputs");
464 if (this->is_Loop() && del_it == LoopNode::EntryControl ||
465 !this->is_Loop() && has_phis && is_unreachable_region(phase)) {
466 // Yes, the region will be removed during the next step below.
467 // Cut the backedge input and remove phis since no data paths left.
468 // We don't cut outputs to other nodes here since we need to put them
469 // on the worklist.
470 del_req(1);
471 cnt = 0;
472 assert( req() == 1, "no more inputs expected" );
473 uint max = outcnt();
474 bool progress = true;
475 Node *top = phase->C->top();
476 PhaseIterGVN *igvn = phase->is_IterGVN();
477 DUIterator j;
478 while(progress) {
479 progress = false;
480 for (j = outs(); has_out(j); j++) {
481 Node *n = out(j);
482 if( n->is_Phi() ) {
483 assert( igvn->eqv(n->in(0), this), "" );
484 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
485 // Break dead loop data path.
486 // Eagerly replace phis with top to avoid phis copies generation.
487 igvn->replace_node(n, top);
488 if( max != outcnt() ) {
489 progress = true;
490 j = refresh_out_pos(j);
491 max = outcnt();
492 }
493 }
494 }
495 }
496 add_to_worklist = true;
497 }
498 }
499 if (add_to_worklist) {
500 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
501 }
503 if( cnt <= 1 ) { // Only 1 path in?
504 set_req(0, NULL); // Null control input for region copy
505 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
506 // No inputs or all inputs are NULL.
507 return NULL;
508 } else if (can_reshape) { // Optimization phase - remove the node
509 PhaseIterGVN *igvn = phase->is_IterGVN();
510 Node *parent_ctrl;
511 if( cnt == 0 ) {
512 assert( req() == 1, "no inputs expected" );
513 // During IGVN phase such region will be subsumed by TOP node
514 // so region's phis will have TOP as control node.
515 // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
516 // Also set other user's input to top.
517 parent_ctrl = phase->C->top();
518 } else {
519 // The fallthrough case since we already checked dead loops above.
520 parent_ctrl = in(1);
521 assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
522 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
523 }
524 if (!add_to_worklist)
525 igvn->add_users_to_worklist(this); // Check for further allowed opts
526 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
527 Node* n = last_out(i);
528 igvn->hash_delete(n); // Remove from worklist before modifying edges
529 if( n->is_Phi() ) { // Collapse all Phis
530 // Eagerly replace phis to avoid copies generation.
531 Node* in;
532 if( cnt == 0 ) {
533 assert( n->req() == 1, "No data inputs expected" );
534 in = parent_ctrl; // replaced by top
535 } else {
536 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
537 in = n->in(1); // replaced by unique input
538 if( n->as_Phi()->is_unsafe_data_reference(in) )
539 in = phase->C->top(); // replaced by top
540 }
541 igvn->replace_node(n, in);
542 }
543 else if( n->is_Region() ) { // Update all incoming edges
544 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
545 uint uses_found = 0;
546 for( uint k=1; k < n->req(); k++ ) {
547 if( n->in(k) == this ) {
548 n->set_req(k, parent_ctrl);
549 uses_found++;
550 }
551 }
552 if( uses_found > 1 ) { // (--i) done at the end of the loop.
553 i -= (uses_found - 1);
554 }
555 }
556 else {
557 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
558 n->set_req(0, parent_ctrl);
559 }
560 #ifdef ASSERT
561 for( uint k=0; k < n->req(); k++ ) {
562 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
563 }
564 #endif
565 }
566 // Remove the RegionNode itself from DefUse info
567 igvn->remove_dead_node(this);
568 return NULL;
569 }
570 return this; // Record progress
571 }
574 // If a Region flows into a Region, merge into one big happy merge.
575 if (can_reshape) {
576 Node *m = merge_region(this, phase);
577 if (m != NULL) return m;
578 }
580 // Check if this region is the root of a clipping idiom on floats
581 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
582 // Check that only one use is a Phi and that it simplifies to two constants +
583 PhiNode* phi = has_unique_phi();
584 if (phi != NULL) { // One Phi user
585 // Check inputs to the Phi
586 ConNode *min;
587 ConNode *max;
588 Node *val;
589 uint min_idx;
590 uint max_idx;
591 uint val_idx;
592 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
593 IfNode *top_if;
594 IfNode *bot_if;
595 if( check_if_clipping( this, bot_if, top_if ) ) {
596 // Control pattern checks, now verify compares
597 Node *top_in = NULL; // value being compared against
598 Node *bot_in = NULL;
599 if( check_compare_clipping( true, bot_if, min, bot_in ) &&
600 check_compare_clipping( false, top_if, max, top_in ) ) {
601 if( bot_in == top_in ) {
602 PhaseIterGVN *gvn = phase->is_IterGVN();
603 assert( gvn != NULL, "Only had DefUse info in IterGVN");
604 // Only remaining check is that bot_in == top_in == (Phi's val + mods)
606 // Check for the ConvF2INode
607 ConvF2INode *convf2i;
608 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
609 convf2i->in(1) == bot_in ) {
610 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
611 // max test
612 Node *cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, min ));
613 Node *boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::lt ));
614 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 ));
615 Node *if_min= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
616 Node *ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
617 // min test
618 cmp = gvn->register_new_node_with_optimizer(new (phase->C, 3) CmpINode( convf2i, max ));
619 boo = gvn->register_new_node_with_optimizer(new (phase->C, 2) BoolNode( cmp, BoolTest::gt ));
620 iff = (IfNode*)gvn->register_new_node_with_optimizer(new (phase->C, 2) IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
621 Node *if_max= gvn->register_new_node_with_optimizer(new (phase->C, 1) IfTrueNode (iff));
622 ifF = gvn->register_new_node_with_optimizer(new (phase->C, 1) IfFalseNode(iff));
623 // update input edges to region node
624 set_req_X( min_idx, if_min, gvn );
625 set_req_X( max_idx, if_max, gvn );
626 set_req_X( val_idx, ifF, gvn );
627 // remove unnecessary 'LShiftI; RShiftI' idiom
628 gvn->hash_delete(phi);
629 phi->set_req_X( val_idx, convf2i, gvn );
630 gvn->hash_find_insert(phi);
631 // Return transformed region node
632 return this;
633 }
634 }
635 }
636 }
637 }
638 }
639 }
641 return NULL;
642 }
646 const RegMask &RegionNode::out_RegMask() const {
647 return RegMask::Empty;
648 }
650 // Find the one non-null required input. RegionNode only
651 Node *Node::nonnull_req() const {
652 assert( is_Region(), "" );
653 for( uint i = 1; i < _cnt; i++ )
654 if( in(i) )
655 return in(i);
656 ShouldNotReachHere();
657 return NULL;
658 }
661 //=============================================================================
662 // note that these functions assume that the _adr_type field is flattened
663 uint PhiNode::hash() const {
664 const Type* at = _adr_type;
665 return TypeNode::hash() + (at ? at->hash() : 0);
666 }
667 uint PhiNode::cmp( const Node &n ) const {
668 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
669 }
670 static inline
671 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
672 if (at == NULL || at == TypePtr::BOTTOM) return at;
673 return Compile::current()->alias_type(at)->adr_type();
674 }
676 //----------------------------make---------------------------------------------
677 // create a new phi with edges matching r and set (initially) to x
678 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
679 uint preds = r->req(); // Number of predecessor paths
680 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
681 PhiNode* p = new (Compile::current(), preds) PhiNode(r, t, at);
682 for (uint j = 1; j < preds; j++) {
683 // Fill in all inputs, except those which the region does not yet have
684 if (r->in(j) != NULL)
685 p->init_req(j, x);
686 }
687 return p;
688 }
689 PhiNode* PhiNode::make(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 make(r, x, t, at);
694 }
695 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
696 const Type* t = x->bottom_type();
697 const TypePtr* at = NULL;
698 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
699 return new (Compile::current(), r->req()) PhiNode(r, t, at);
700 }
703 //------------------------slice_memory-----------------------------------------
704 // create a new phi with narrowed memory type
705 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
706 PhiNode* mem = (PhiNode*) clone();
707 *(const TypePtr**)&mem->_adr_type = adr_type;
708 // convert self-loops, or else we get a bad graph
709 for (uint i = 1; i < req(); i++) {
710 if ((const Node*)in(i) == this) mem->set_req(i, mem);
711 }
712 mem->verify_adr_type();
713 return mem;
714 }
716 //------------------------split_out_instance-----------------------------------
717 // Split out an instance type from a bottom phi.
718 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
719 const TypeOopPtr *t_oop = at->isa_oopptr();
720 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
721 const TypePtr *t = adr_type();
722 assert(type() == Type::MEMORY &&
723 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
724 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
725 t->is_oopptr()->cast_to_exactness(true)
726 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
727 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
728 "bottom or raw memory required");
730 // Check if an appropriate node already exists.
731 Node *region = in(0);
732 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
733 Node* use = region->fast_out(k);
734 if( use->is_Phi()) {
735 PhiNode *phi2 = use->as_Phi();
736 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
737 return phi2;
738 }
739 }
740 }
741 Compile *C = igvn->C;
742 Arena *a = Thread::current()->resource_area();
743 Node_Array node_map = new Node_Array(a);
744 Node_Stack stack(a, C->unique() >> 4);
745 PhiNode *nphi = slice_memory(at);
746 igvn->register_new_node_with_optimizer( nphi );
747 node_map.map(_idx, nphi);
748 stack.push((Node *)this, 1);
749 while(!stack.is_empty()) {
750 PhiNode *ophi = stack.node()->as_Phi();
751 uint i = stack.index();
752 assert(i >= 1, "not control edge");
753 stack.pop();
754 nphi = node_map[ophi->_idx]->as_Phi();
755 for (; i < ophi->req(); i++) {
756 Node *in = ophi->in(i);
757 if (in == NULL || igvn->type(in) == Type::TOP)
758 continue;
759 Node *opt = MemNode::optimize_simple_memory_chain(in, at, igvn);
760 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
761 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
762 opt = node_map[optphi->_idx];
763 if (opt == NULL) {
764 stack.push(ophi, i);
765 nphi = optphi->slice_memory(at);
766 igvn->register_new_node_with_optimizer( nphi );
767 node_map.map(optphi->_idx, nphi);
768 ophi = optphi;
769 i = 0; // will get incremented at top of loop
770 continue;
771 }
772 }
773 nphi->set_req(i, opt);
774 }
775 }
776 return nphi;
777 }
779 //------------------------verify_adr_type--------------------------------------
780 #ifdef ASSERT
781 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
782 if (visited.test_set(_idx)) return; //already visited
784 // recheck constructor invariants:
785 verify_adr_type(false);
787 // recheck local phi/phi consistency:
788 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
789 "adr_type must be consistent across phi nest");
791 // walk around
792 for (uint i = 1; i < req(); i++) {
793 Node* n = in(i);
794 if (n == NULL) continue;
795 const Node* np = in(i);
796 if (np->is_Phi()) {
797 np->as_Phi()->verify_adr_type(visited, at);
798 } else if (n->bottom_type() == Type::TOP
799 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
800 // ignore top inputs
801 } else {
802 const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
803 // recheck phi/non-phi consistency at leaves:
804 assert((nat != NULL) == (at != NULL), "");
805 assert(nat == at || nat == TypePtr::BOTTOM,
806 "adr_type must be consistent at leaves of phi nest");
807 }
808 }
809 }
811 // Verify a whole nest of phis rooted at this one.
812 void PhiNode::verify_adr_type(bool recursive) const {
813 if (is_error_reported()) return; // muzzle asserts when debugging an error
814 if (Node::in_dump()) return; // muzzle asserts when printing
816 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
818 if (!VerifyAliases) return; // verify thoroughly only if requested
820 assert(_adr_type == flatten_phi_adr_type(_adr_type),
821 "Phi::adr_type must be pre-normalized");
823 if (recursive) {
824 VectorSet visited(Thread::current()->resource_area());
825 verify_adr_type(visited, _adr_type);
826 }
827 }
828 #endif
831 //------------------------------Value------------------------------------------
832 // Compute the type of the PhiNode
833 const Type *PhiNode::Value( PhaseTransform *phase ) const {
834 Node *r = in(0); // RegionNode
835 if( !r ) // Copy or dead
836 return in(1) ? phase->type(in(1)) : Type::TOP;
838 // Note: During parsing, phis are often transformed before their regions.
839 // This means we have to use type_or_null to defend against untyped regions.
840 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
841 return Type::TOP;
843 // Check for trip-counted loop. If so, be smarter.
844 CountedLoopNode *l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
845 if( l && l->can_be_counted_loop(phase) &&
846 ((const Node*)l->phi() == this) ) { // Trip counted loop!
847 // protect against init_trip() or limit() returning NULL
848 const Node *init = l->init_trip();
849 const Node *limit = l->limit();
850 if( init != NULL && limit != NULL && l->stride_is_con() ) {
851 const TypeInt *lo = init ->bottom_type()->isa_int();
852 const TypeInt *hi = limit->bottom_type()->isa_int();
853 if( lo && hi ) { // Dying loops might have TOP here
854 int stride = l->stride_con();
855 if( stride < 0 ) { // Down-counter loop
856 const TypeInt *tmp = lo; lo = hi; hi = tmp;
857 stride = -stride;
858 }
859 if( lo->_hi < hi->_lo ) // Reversed endpoints are well defined :-(
860 return TypeInt::make(lo->_lo,hi->_hi,3);
861 }
862 }
863 }
865 // Until we have harmony between classes and interfaces in the type
866 // lattice, we must tread carefully around phis which implicitly
867 // convert the one to the other.
868 const TypePtr* ttp = _type->make_ptr();
869 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
870 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
871 bool is_intf = false;
872 if (ttip != NULL) {
873 ciKlass* k = ttip->klass();
874 if (k->is_loaded() && k->is_interface())
875 is_intf = true;
876 }
877 if (ttkp != NULL) {
878 ciKlass* k = ttkp->klass();
879 if (k->is_loaded() && k->is_interface())
880 is_intf = true;
881 }
883 // Default case: merge all inputs
884 const Type *t = Type::TOP; // Merged type starting value
885 for (uint i = 1; i < req(); ++i) {// For all paths in
886 // Reachable control path?
887 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
888 const Type* ti = phase->type(in(i));
889 // We assume that each input of an interface-valued Phi is a true
890 // subtype of that interface. This might not be true of the meet
891 // of all the input types. The lattice is not distributive in
892 // such cases. Ward off asserts in type.cpp by refusing to do
893 // meets between interfaces and proper classes.
894 const TypePtr* tip = ti->make_ptr();
895 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
896 if (tiip) {
897 bool ti_is_intf = false;
898 ciKlass* k = tiip->klass();
899 if (k->is_loaded() && k->is_interface())
900 ti_is_intf = true;
901 if (is_intf != ti_is_intf)
902 { t = _type; break; }
903 }
904 t = t->meet(ti);
905 }
906 }
908 // The worst-case type (from ciTypeFlow) should be consistent with "t".
909 // That is, we expect that "t->higher_equal(_type)" holds true.
910 // There are various exceptions:
911 // - Inputs which are phis might in fact be widened unnecessarily.
912 // For example, an input might be a widened int while the phi is a short.
913 // - Inputs might be BotPtrs but this phi is dependent on a null check,
914 // and postCCP has removed the cast which encodes the result of the check.
915 // - The type of this phi is an interface, and the inputs are classes.
916 // - Value calls on inputs might produce fuzzy results.
917 // (Occurrences of this case suggest improvements to Value methods.)
918 //
919 // It is not possible to see Type::BOTTOM values as phi inputs,
920 // because the ciTypeFlow pre-pass produces verifier-quality types.
921 const Type* ft = t->filter(_type); // Worst case type
923 #ifdef ASSERT
924 // The following logic has been moved into TypeOopPtr::filter.
925 const Type* jt = t->join(_type);
926 if( jt->empty() ) { // Emptied out???
928 // Check for evil case of 't' being a class and '_type' expecting an
929 // interface. This can happen because the bytecodes do not contain
930 // enough type info to distinguish a Java-level interface variable
931 // from a Java-level object variable. If we meet 2 classes which
932 // both implement interface I, but their meet is at 'j/l/O' which
933 // doesn't implement I, we have no way to tell if the result should
934 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
935 // into a Phi which "knows" it's an Interface type we'll have to
936 // uplift the type.
937 if( !t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface() )
938 { assert(ft == _type, ""); } // Uplift to interface
939 else if( !t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface() )
940 { assert(ft == _type, ""); } // Uplift to interface
941 // Otherwise it's something stupid like non-overlapping int ranges
942 // found on dying counted loops.
943 else
944 { assert(ft == Type::TOP, ""); } // Canonical empty value
945 }
947 else {
949 // If we have an interface-typed Phi and we narrow to a class type, the join
950 // should report back the class. However, if we have a J/L/Object
951 // class-typed Phi and an interface flows in, it's possible that the meet &
952 // join report an interface back out. This isn't possible but happens
953 // because the type system doesn't interact well with interfaces.
954 const TypePtr *jtp = jt->make_ptr();
955 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
956 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
957 if( jtip && ttip ) {
958 if( jtip->is_loaded() && jtip->klass()->is_interface() &&
959 ttip->is_loaded() && !ttip->klass()->is_interface() ) {
960 // Happens in a CTW of rt.jar, 320-341, no extra flags
961 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
962 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
963 jt = ft;
964 }
965 }
966 if( jtkp && ttkp ) {
967 if( jtkp->is_loaded() && jtkp->klass()->is_interface() &&
968 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
969 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
970 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
971 ft->isa_narrowoop() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
972 jt = ft;
973 }
974 }
975 if (jt != ft && jt->base() == ft->base()) {
976 if (jt->isa_int() &&
977 jt->is_int()->_lo == ft->is_int()->_lo &&
978 jt->is_int()->_hi == ft->is_int()->_hi)
979 jt = ft;
980 if (jt->isa_long() &&
981 jt->is_long()->_lo == ft->is_long()->_lo &&
982 jt->is_long()->_hi == ft->is_long()->_hi)
983 jt = ft;
984 }
985 if (jt != ft) {
986 tty->print("merge type: "); t->dump(); tty->cr();
987 tty->print("kill type: "); _type->dump(); tty->cr();
988 tty->print("join type: "); jt->dump(); tty->cr();
989 tty->print("filter type: "); ft->dump(); tty->cr();
990 }
991 assert(jt == ft, "");
992 }
993 #endif //ASSERT
995 // Deal with conversion problems found in data loops.
996 ft = phase->saturate(ft, phase->type_or_null(this), _type);
998 return ft;
999 }
1002 //------------------------------is_diamond_phi---------------------------------
1003 // Does this Phi represent a simple well-shaped diamond merge? Return the
1004 // index of the true path or 0 otherwise.
1005 int PhiNode::is_diamond_phi() const {
1006 // Check for a 2-path merge
1007 Node *region = in(0);
1008 if( !region ) return 0;
1009 if( region->req() != 3 ) return 0;
1010 if( req() != 3 ) return 0;
1011 // Check that both paths come from the same If
1012 Node *ifp1 = region->in(1);
1013 Node *ifp2 = region->in(2);
1014 if( !ifp1 || !ifp2 ) return 0;
1015 Node *iff = ifp1->in(0);
1016 if( !iff || !iff->is_If() ) return 0;
1017 if( iff != ifp2->in(0) ) return 0;
1018 // Check for a proper bool/cmp
1019 const Node *b = iff->in(1);
1020 if( !b->is_Bool() ) return 0;
1021 const Node *cmp = b->in(1);
1022 if( !cmp->is_Cmp() ) return 0;
1024 // Check for branching opposite expected
1025 if( ifp2->Opcode() == Op_IfTrue ) {
1026 assert( ifp1->Opcode() == Op_IfFalse, "" );
1027 return 2;
1028 } else {
1029 assert( ifp1->Opcode() == Op_IfTrue, "" );
1030 return 1;
1031 }
1032 }
1034 //----------------------------check_cmove_id-----------------------------------
1035 // Check for CMove'ing a constant after comparing against the constant.
1036 // Happens all the time now, since if we compare equality vs a constant in
1037 // the parser, we "know" the variable is constant on one path and we force
1038 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1039 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
1040 // general in that we don't need constants. Since CMove's are only inserted
1041 // in very special circumstances, we do it here on generic Phi's.
1042 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1043 assert(true_path !=0, "only diamond shape graph expected");
1045 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1046 // phi->region->if_proj->ifnode->bool->cmp
1047 Node* region = in(0);
1048 Node* iff = region->in(1)->in(0);
1049 BoolNode* b = iff->in(1)->as_Bool();
1050 Node* cmp = b->in(1);
1051 Node* tval = in(true_path);
1052 Node* fval = in(3-true_path);
1053 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1054 if (id == NULL)
1055 return NULL;
1057 // Either value might be a cast that depends on a branch of 'iff'.
1058 // Since the 'id' value will float free of the diamond, either
1059 // decast or return failure.
1060 Node* ctl = id->in(0);
1061 if (ctl != NULL && ctl->in(0) == iff) {
1062 if (id->is_ConstraintCast()) {
1063 return id->in(1);
1064 } else {
1065 // Don't know how to disentangle this value.
1066 return NULL;
1067 }
1068 }
1070 return id;
1071 }
1073 //------------------------------Identity---------------------------------------
1074 // Check for Region being Identity.
1075 Node *PhiNode::Identity( PhaseTransform *phase ) {
1076 // Check for no merging going on
1077 // (There used to be special-case code here when this->region->is_Loop.
1078 // It would check for a tributary phi on the backedge that the main phi
1079 // trivially, perhaps with a single cast. The unique_input method
1080 // does all this and more, by reducing such tributaries to 'this'.)
1081 Node* uin = unique_input(phase);
1082 if (uin != NULL) {
1083 return uin;
1084 }
1086 int true_path = is_diamond_phi();
1087 if (true_path != 0) {
1088 Node* id = is_cmove_id(phase, true_path);
1089 if (id != NULL) return id;
1090 }
1092 return this; // No identity
1093 }
1095 //-----------------------------unique_input------------------------------------
1096 // Find the unique value, discounting top, self-loops, and casts.
1097 // Return top if there are no inputs, and self if there are multiple.
1098 Node* PhiNode::unique_input(PhaseTransform* phase) {
1099 // 1) One unique direct input, or
1100 // 2) some of the inputs have an intervening ConstraintCast and
1101 // the type of input is the same or sharper (more specific)
1102 // than the phi's type.
1103 // 3) an input is a self loop
1104 //
1105 // 1) input or 2) input or 3) input __
1106 // / \ / \ \ / \
1107 // \ / | cast phi cast
1108 // phi \ / / \ /
1109 // phi / --
1111 Node* r = in(0); // RegionNode
1112 if (r == NULL) return in(1); // Already degraded to a Copy
1113 Node* uncasted_input = NULL; // The unique uncasted input (ConstraintCasts removed)
1114 Node* direct_input = NULL; // The unique direct input
1116 for (uint i = 1, cnt = req(); i < cnt; ++i) {
1117 Node* rc = r->in(i);
1118 if (rc == NULL || phase->type(rc) == Type::TOP)
1119 continue; // ignore unreachable control path
1120 Node* n = in(i);
1121 if (n == NULL)
1122 continue;
1123 Node* un = n->uncast();
1124 if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1125 continue; // ignore if top, or in(i) and "this" are in a data cycle
1126 }
1127 // Check for a unique uncasted input
1128 if (uncasted_input == NULL) {
1129 uncasted_input = un;
1130 } else if (uncasted_input != un) {
1131 uncasted_input = NodeSentinel; // no unique uncasted input
1132 }
1133 // Check for a unique direct input
1134 if (direct_input == NULL) {
1135 direct_input = n;
1136 } else if (direct_input != n) {
1137 direct_input = NodeSentinel; // no unique direct input
1138 }
1139 }
1140 if (direct_input == NULL) {
1141 return phase->C->top(); // no inputs
1142 }
1143 assert(uncasted_input != NULL,"");
1145 if (direct_input != NodeSentinel) {
1146 return direct_input; // one unique direct input
1147 }
1148 if (uncasted_input != NodeSentinel &&
1149 phase->type(uncasted_input)->higher_equal(type())) {
1150 return uncasted_input; // one unique uncasted input
1151 }
1153 // Nothing.
1154 return NULL;
1155 }
1157 //------------------------------is_x2logic-------------------------------------
1158 // Check for simple convert-to-boolean pattern
1159 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1160 // Convert Phi to an ConvIB.
1161 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1162 assert(true_path !=0, "only diamond shape graph expected");
1163 // Convert the true/false index into an expected 0/1 return.
1164 // Map 2->0 and 1->1.
1165 int flipped = 2-true_path;
1167 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1168 // phi->region->if_proj->ifnode->bool->cmp
1169 Node *region = phi->in(0);
1170 Node *iff = region->in(1)->in(0);
1171 BoolNode *b = (BoolNode*)iff->in(1);
1172 const CmpNode *cmp = (CmpNode*)b->in(1);
1174 Node *zero = phi->in(1);
1175 Node *one = phi->in(2);
1176 const Type *tzero = phase->type( zero );
1177 const Type *tone = phase->type( one );
1179 // Check for compare vs 0
1180 const Type *tcmp = phase->type(cmp->in(2));
1181 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1182 // Allow cmp-vs-1 if the other input is bounded by 0-1
1183 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1184 return NULL;
1185 flipped = 1-flipped; // Test is vs 1 instead of 0!
1186 }
1188 // Check for setting zero/one opposite expected
1189 if( tzero == TypeInt::ZERO ) {
1190 if( tone == TypeInt::ONE ) {
1191 } else return NULL;
1192 } else if( tzero == TypeInt::ONE ) {
1193 if( tone == TypeInt::ZERO ) {
1194 flipped = 1-flipped;
1195 } else return NULL;
1196 } else return NULL;
1198 // Check for boolean test backwards
1199 if( b->_test._test == BoolTest::ne ) {
1200 } else if( b->_test._test == BoolTest::eq ) {
1201 flipped = 1-flipped;
1202 } else return NULL;
1204 // Build int->bool conversion
1205 Node *n = new (phase->C, 2) Conv2BNode( cmp->in(1) );
1206 if( flipped )
1207 n = new (phase->C, 3) XorINode( phase->transform(n), phase->intcon(1) );
1209 return n;
1210 }
1212 //------------------------------is_cond_add------------------------------------
1213 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
1214 // To be profitable the control flow has to disappear; there can be no other
1215 // values merging here. We replace the test-and-branch with:
1216 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
1217 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1218 // Then convert Y to 0-or-Y and finally add.
1219 // This is a key transform for SpecJava _201_compress.
1220 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1221 assert(true_path !=0, "only diamond shape graph expected");
1223 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1224 // phi->region->if_proj->ifnode->bool->cmp
1225 RegionNode *region = (RegionNode*)phi->in(0);
1226 Node *iff = region->in(1)->in(0);
1227 BoolNode* b = iff->in(1)->as_Bool();
1228 const CmpNode *cmp = (CmpNode*)b->in(1);
1230 // Make sure only merging this one phi here
1231 if (region->has_unique_phi() != phi) return NULL;
1233 // Make sure each arm of the diamond has exactly one output, which we assume
1234 // is the region. Otherwise, the control flow won't disappear.
1235 if (region->in(1)->outcnt() != 1) return NULL;
1236 if (region->in(2)->outcnt() != 1) return NULL;
1238 // Check for "(P < Q)" of type signed int
1239 if (b->_test._test != BoolTest::lt) return NULL;
1240 if (cmp->Opcode() != Op_CmpI) return NULL;
1242 Node *p = cmp->in(1);
1243 Node *q = cmp->in(2);
1244 Node *n1 = phi->in( true_path);
1245 Node *n2 = phi->in(3-true_path);
1247 int op = n1->Opcode();
1248 if( op != Op_AddI // Need zero as additive identity
1249 /*&&op != Op_SubI &&
1250 op != Op_AddP &&
1251 op != Op_XorI &&
1252 op != Op_OrI*/ )
1253 return NULL;
1255 Node *x = n2;
1256 Node *y = n1->in(1);
1257 if( n2 == n1->in(1) ) {
1258 y = n1->in(2);
1259 } else if( n2 == n1->in(1) ) {
1260 } else return NULL;
1262 // Not so profitable if compare and add are constants
1263 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1264 return NULL;
1266 Node *cmplt = phase->transform( new (phase->C, 3) CmpLTMaskNode(p,q) );
1267 Node *j_and = phase->transform( new (phase->C, 3) AndINode(cmplt,y) );
1268 return new (phase->C, 3) AddINode(j_and,x);
1269 }
1271 //------------------------------is_absolute------------------------------------
1272 // Check for absolute value.
1273 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1274 assert(true_path !=0, "only diamond shape graph expected");
1276 int cmp_zero_idx = 0; // Index of compare input where to look for zero
1277 int phi_x_idx = 0; // Index of phi input where to find naked x
1279 // ABS ends with the merge of 2 control flow paths.
1280 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1281 int false_path = 3 - true_path;
1283 // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1284 // phi->region->if_proj->ifnode->bool->cmp
1285 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1287 // Check bool sense
1288 switch( bol->_test._test ) {
1289 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
1290 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1291 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
1292 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1293 default: return NULL; break;
1294 }
1296 // Test is next
1297 Node *cmp = bol->in(1);
1298 const Type *tzero = NULL;
1299 switch( cmp->Opcode() ) {
1300 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
1301 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
1302 default: return NULL;
1303 }
1305 // Find zero input of compare; the other input is being abs'd
1306 Node *x = NULL;
1307 bool flip = false;
1308 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1309 x = cmp->in(3 - cmp_zero_idx);
1310 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1311 // The test is inverted, we should invert the result...
1312 x = cmp->in(cmp_zero_idx);
1313 flip = true;
1314 } else {
1315 return NULL;
1316 }
1318 // Next get the 2 pieces being selected, one is the original value
1319 // and the other is the negated value.
1320 if( phi_root->in(phi_x_idx) != x ) return NULL;
1322 // Check other phi input for subtract node
1323 Node *sub = phi_root->in(3 - phi_x_idx);
1325 // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1326 if( tzero == TypeF::ZERO ) {
1327 if( sub->Opcode() != Op_SubF ||
1328 sub->in(2) != x ||
1329 phase->type(sub->in(1)) != tzero ) return NULL;
1330 x = new (phase->C, 2) AbsFNode(x);
1331 if (flip) {
1332 x = new (phase->C, 3) SubFNode(sub->in(1), phase->transform(x));
1333 }
1334 } else {
1335 if( sub->Opcode() != Op_SubD ||
1336 sub->in(2) != x ||
1337 phase->type(sub->in(1)) != tzero ) return NULL;
1338 x = new (phase->C, 2) AbsDNode(x);
1339 if (flip) {
1340 x = new (phase->C, 3) SubDNode(sub->in(1), phase->transform(x));
1341 }
1342 }
1344 return x;
1345 }
1347 //------------------------------split_once-------------------------------------
1348 // Helper for split_flow_path
1349 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1350 igvn->hash_delete(n); // Remove from hash before hacking edges
1352 Node* predicate_proj = NULL;
1353 uint j = 1;
1354 for (uint i = phi->req()-1; i > 0; i--) {
1355 if (phi->in(i) == val) { // Found a path with val?
1356 if (n->is_Region()) {
1357 Node* proj = PhaseIdealLoop::find_predicate(n->in(i));
1358 if (proj != NULL) {
1359 assert(predicate_proj == NULL, "only one predicate entry expected");
1360 predicate_proj = proj;
1361 }
1362 }
1363 // Add to NEW Region/Phi, no DU info
1364 newn->set_req( j++, n->in(i) );
1365 // Remove from OLD Region/Phi
1366 n->del_req(i);
1367 }
1368 }
1370 // Register the new node but do not transform it. Cannot transform until the
1371 // entire Region/Phi conglomerate has been hacked as a single huge transform.
1372 igvn->register_new_node_with_optimizer( newn );
1374 // Clone loop predicates
1375 if (predicate_proj != NULL) {
1376 newn = igvn->clone_loop_predicates(predicate_proj, newn);
1377 }
1379 // Now I can point to the new node.
1380 n->add_req(newn);
1381 igvn->_worklist.push(n);
1382 }
1384 //------------------------------split_flow_path--------------------------------
1385 // Check for merging identical values and split flow paths
1386 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1387 BasicType bt = phi->type()->basic_type();
1388 if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1389 return NULL; // Bail out on funny non-value stuff
1390 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a
1391 return NULL; // third unequal input to be worth doing
1393 // Scan for a constant
1394 uint i;
1395 for( i = 1; i < phi->req()-1; i++ ) {
1396 Node *n = phi->in(i);
1397 if( !n ) return NULL;
1398 if( phase->type(n) == Type::TOP ) return NULL;
1399 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN )
1400 break;
1401 }
1402 if( i >= phi->req() ) // Only split for constants
1403 return NULL;
1405 Node *val = phi->in(i); // Constant to split for
1406 uint hit = 0; // Number of times it occurs
1408 for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1409 Node *n = phi->in(i);
1410 if( !n ) return NULL;
1411 if( phase->type(n) == Type::TOP ) return NULL;
1412 if( phi->in(i) == val )
1413 hit++;
1414 }
1416 if( hit <= 1 || // Make sure we find 2 or more
1417 hit == phi->req()-1 ) // and not ALL the same value
1418 return NULL;
1420 // Now start splitting out the flow paths that merge the same value.
1421 // Split first the RegionNode.
1422 PhaseIterGVN *igvn = phase->is_IterGVN();
1423 Node *r = phi->region();
1424 RegionNode *newr = new (phase->C, hit+1) RegionNode(hit+1);
1425 split_once(igvn, phi, val, r, newr);
1427 // Now split all other Phis than this one
1428 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1429 Node* phi2 = r->fast_out(k);
1430 if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1431 PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1432 split_once(igvn, phi, val, phi2, newphi);
1433 }
1434 }
1436 // Clean up this guy
1437 igvn->hash_delete(phi);
1438 for( i = phi->req()-1; i > 0; i-- ) {
1439 if( phi->in(i) == val ) {
1440 phi->del_req(i);
1441 }
1442 }
1443 phi->add_req(val);
1445 return phi;
1446 }
1448 //=============================================================================
1449 //------------------------------simple_data_loop_check-------------------------
1450 // Try to determining if the phi node in a simple safe/unsafe data loop.
1451 // Returns:
1452 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1453 // Safe - safe case when the phi and it's inputs reference only safe data
1454 // nodes;
1455 // Unsafe - the phi and it's inputs reference unsafe data nodes but there
1456 // is no reference back to the phi - need a graph walk
1457 // to determine if it is in a loop;
1458 // UnsafeLoop - unsafe case when the phi references itself directly or through
1459 // unsafe data node.
1460 // Note: a safe data node is a node which could/never reference itself during
1461 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1462 // I mark Phi nodes as safe node not only because they can reference itself
1463 // but also to prevent mistaking the fallthrough case inside an outer loop
1464 // as dead loop when the phi references itselfs through an other phi.
1465 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1466 // It is unsafe loop if the phi node references itself directly.
1467 if (in == (Node*)this)
1468 return UnsafeLoop; // Unsafe loop
1469 // Unsafe loop if the phi node references itself through an unsafe data node.
1470 // Exclude cases with null inputs or data nodes which could reference
1471 // itself (safe for dead loops).
1472 if (in != NULL && !in->is_dead_loop_safe()) {
1473 // Check inputs of phi's inputs also.
1474 // It is much less expensive then full graph walk.
1475 uint cnt = in->req();
1476 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1;
1477 for (; i < cnt; ++i) {
1478 Node* m = in->in(i);
1479 if (m == (Node*)this)
1480 return UnsafeLoop; // Unsafe loop
1481 if (m != NULL && !m->is_dead_loop_safe()) {
1482 // Check the most common case (about 30% of all cases):
1483 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1484 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1485 if (m1 == (Node*)this)
1486 return UnsafeLoop; // Unsafe loop
1487 if (m1 != NULL && m1 == m->in(2) &&
1488 m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1489 continue; // Safe case
1490 }
1491 // The phi references an unsafe node - need full analysis.
1492 return Unsafe;
1493 }
1494 }
1495 }
1496 return Safe; // Safe case - we can optimize the phi node.
1497 }
1499 //------------------------------is_unsafe_data_reference-----------------------
1500 // If phi can be reached through the data input - it is data loop.
1501 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1502 assert(req() > 1, "");
1503 // First, check simple cases when phi references itself directly or
1504 // through an other node.
1505 LoopSafety safety = simple_data_loop_check(in);
1506 if (safety == UnsafeLoop)
1507 return true; // phi references itself - unsafe loop
1508 else if (safety == Safe)
1509 return false; // Safe case - phi could be replaced with the unique input.
1511 // Unsafe case when we should go through data graph to determine
1512 // if the phi references itself.
1514 ResourceMark rm;
1516 Arena *a = Thread::current()->resource_area();
1517 Node_List nstack(a);
1518 VectorSet visited(a);
1520 nstack.push(in); // Start with unique input.
1521 visited.set(in->_idx);
1522 while (nstack.size() != 0) {
1523 Node* n = nstack.pop();
1524 uint cnt = n->req();
1525 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1526 for (; i < cnt; i++) {
1527 Node* m = n->in(i);
1528 if (m == (Node*)this) {
1529 return true; // Data loop
1530 }
1531 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1532 if (!visited.test_set(m->_idx))
1533 nstack.push(m);
1534 }
1535 }
1536 }
1537 return false; // The phi is not reachable from its inputs
1538 }
1541 //------------------------------Ideal------------------------------------------
1542 // Return a node which is more "ideal" than the current node. Must preserve
1543 // the CFG, but we can still strip out dead paths.
1544 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1545 // The next should never happen after 6297035 fix.
1546 if( is_copy() ) // Already degraded to a Copy ?
1547 return NULL; // No change
1549 Node *r = in(0); // RegionNode
1550 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1552 // Note: During parsing, phis are often transformed before their regions.
1553 // This means we have to use type_or_null to defend against untyped regions.
1554 if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1555 return NULL; // No change
1557 Node *top = phase->C->top();
1558 bool new_phi = (outcnt() == 0); // transforming new Phi
1559 assert(!can_reshape || !new_phi, "for igvn new phi should be hooked");
1561 // The are 2 situations when only one valid phi's input is left
1562 // (in addition to Region input).
1563 // One: region is not loop - replace phi with this input.
1564 // Two: region is loop - replace phi with top since this data path is dead
1565 // and we need to break the dead data loop.
1566 Node* progress = NULL; // Record if any progress made
1567 for( uint j = 1; j < req(); ++j ){ // For all paths in
1568 // Check unreachable control paths
1569 Node* rc = r->in(j);
1570 Node* n = in(j); // Get the input
1571 if (rc == NULL || phase->type(rc) == Type::TOP) {
1572 if (n != top) { // Not already top?
1573 set_req(j, top); // Nuke it down
1574 progress = this; // Record progress
1575 }
1576 }
1577 }
1579 if (can_reshape && outcnt() == 0) {
1580 // set_req() above may kill outputs if Phi is referenced
1581 // only by itself on the dead (top) control path.
1582 return top;
1583 }
1585 Node* uin = unique_input(phase);
1586 if (uin == top) { // Simplest case: no alive inputs.
1587 if (can_reshape) // IGVN transformation
1588 return top;
1589 else
1590 return NULL; // Identity will return TOP
1591 } else if (uin != NULL) {
1592 // Only one not-NULL unique input path is left.
1593 // Determine if this input is backedge of a loop.
1594 // (Skip new phis which have no uses and dead regions).
1595 if( outcnt() > 0 && r->in(0) != NULL ) {
1596 // First, take the short cut when we know it is a loop and
1597 // the EntryControl data path is dead.
1598 assert(!r->is_Loop() || r->req() == 3, "Loop node should have 3 inputs");
1599 // Then, check if there is a data loop when phi references itself directly
1600 // or through other data nodes.
1601 if( r->is_Loop() && !phase->eqv_uncast(uin, in(LoopNode::EntryControl)) ||
1602 !r->is_Loop() && is_unsafe_data_reference(uin) ) {
1603 // Break this data loop to avoid creation of a dead loop.
1604 if (can_reshape) {
1605 return top;
1606 } else {
1607 // We can't return top if we are in Parse phase - cut inputs only
1608 // let Identity to handle the case.
1609 replace_edge(uin, top);
1610 return NULL;
1611 }
1612 }
1613 }
1615 // One unique input.
1616 debug_only(Node* ident = Identity(phase));
1617 // The unique input must eventually be detected by the Identity call.
1618 #ifdef ASSERT
1619 if (ident != uin && !ident->is_top()) {
1620 // print this output before failing assert
1621 r->dump(3);
1622 this->dump(3);
1623 ident->dump();
1624 uin->dump();
1625 }
1626 #endif
1627 assert(ident == uin || ident->is_top(), "Identity must clean this up");
1628 return NULL;
1629 }
1632 Node* opt = NULL;
1633 int true_path = is_diamond_phi();
1634 if( true_path != 0 ) {
1635 // Check for CMove'ing identity. If it would be unsafe,
1636 // handle it here. In the safe case, let Identity handle it.
1637 Node* unsafe_id = is_cmove_id(phase, true_path);
1638 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1639 opt = unsafe_id;
1641 // Check for simple convert-to-boolean pattern
1642 if( opt == NULL )
1643 opt = is_x2logic(phase, this, true_path);
1645 // Check for absolute value
1646 if( opt == NULL )
1647 opt = is_absolute(phase, this, true_path);
1649 // Check for conditional add
1650 if( opt == NULL && can_reshape )
1651 opt = is_cond_add(phase, this, true_path);
1653 // These 4 optimizations could subsume the phi:
1654 // have to check for a dead data loop creation.
1655 if( opt != NULL ) {
1656 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1657 // Found dead loop.
1658 if( can_reshape )
1659 return top;
1660 // We can't return top if we are in Parse phase - cut inputs only
1661 // to stop further optimizations for this phi. Identity will return TOP.
1662 assert(req() == 3, "only diamond merge phi here");
1663 set_req(1, top);
1664 set_req(2, top);
1665 return NULL;
1666 } else {
1667 return opt;
1668 }
1669 }
1670 }
1672 // Check for merging identical values and split flow paths
1673 if (can_reshape) {
1674 opt = split_flow_path(phase, this);
1675 // This optimization only modifies phi - don't need to check for dead loop.
1676 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1677 if (opt != NULL) return opt;
1678 }
1680 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1681 // Try to undo Phi of AddP:
1682 // (Phi (AddP base base y) (AddP base2 base2 y))
1683 // becomes:
1684 // newbase := (Phi base base2)
1685 // (AddP newbase newbase y)
1686 //
1687 // This occurs as a result of unsuccessful split_thru_phi and
1688 // interferes with taking advantage of addressing modes. See the
1689 // clone_shift_expressions code in matcher.cpp
1690 Node* addp = in(1);
1691 const Type* type = addp->in(AddPNode::Base)->bottom_type();
1692 Node* y = addp->in(AddPNode::Offset);
1693 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1694 // make sure that all the inputs are similar to the first one,
1695 // i.e. AddP with base == address and same offset as first AddP
1696 bool doit = true;
1697 for (uint i = 2; i < req(); i++) {
1698 if (in(i) == NULL ||
1699 in(i)->Opcode() != Op_AddP ||
1700 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1701 in(i)->in(AddPNode::Offset) != y) {
1702 doit = false;
1703 break;
1704 }
1705 // Accumulate type for resulting Phi
1706 type = type->meet(in(i)->in(AddPNode::Base)->bottom_type());
1707 }
1708 Node* base = NULL;
1709 if (doit) {
1710 // Check for neighboring AddP nodes in a tree.
1711 // If they have a base, use that it.
1712 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1713 Node* u = this->fast_out(k);
1714 if (u->is_AddP()) {
1715 Node* base2 = u->in(AddPNode::Base);
1716 if (base2 != NULL && !base2->is_top()) {
1717 if (base == NULL)
1718 base = base2;
1719 else if (base != base2)
1720 { doit = false; break; }
1721 }
1722 }
1723 }
1724 }
1725 if (doit) {
1726 if (base == NULL) {
1727 base = new (phase->C, in(0)->req()) PhiNode(in(0), type, NULL);
1728 for (uint i = 1; i < req(); i++) {
1729 base->init_req(i, in(i)->in(AddPNode::Base));
1730 }
1731 phase->is_IterGVN()->register_new_node_with_optimizer(base);
1732 }
1733 return new (phase->C, 4) AddPNode(base, base, y);
1734 }
1735 }
1736 }
1738 // Split phis through memory merges, so that the memory merges will go away.
1739 // Piggy-back this transformation on the search for a unique input....
1740 // It will be as if the merged memory is the unique value of the phi.
1741 // (Do not attempt this optimization unless parsing is complete.
1742 // It would make the parser's memory-merge logic sick.)
1743 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1744 if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1745 // see if this phi should be sliced
1746 uint merge_width = 0;
1747 bool saw_self = false;
1748 for( uint i=1; i<req(); ++i ) {// For all paths in
1749 Node *ii = in(i);
1750 if (ii->is_MergeMem()) {
1751 MergeMemNode* n = ii->as_MergeMem();
1752 merge_width = MAX2(merge_width, n->req());
1753 saw_self = saw_self || phase->eqv(n->base_memory(), this);
1754 }
1755 }
1757 // This restriction is temporarily necessary to ensure termination:
1758 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0;
1760 if (merge_width > Compile::AliasIdxRaw) {
1761 // found at least one non-empty MergeMem
1762 const TypePtr* at = adr_type();
1763 if (at != TypePtr::BOTTOM) {
1764 // Patch the existing phi to select an input from the merge:
1765 // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1766 // Phi:AT1(...m1...)
1767 int alias_idx = phase->C->get_alias_index(at);
1768 for (uint i=1; i<req(); ++i) {
1769 Node *ii = in(i);
1770 if (ii->is_MergeMem()) {
1771 MergeMemNode* n = ii->as_MergeMem();
1772 // compress paths and change unreachable cycles to TOP
1773 // If not, we can update the input infinitely along a MergeMem cycle
1774 // Equivalent code is in MemNode::Ideal_common
1775 Node *m = phase->transform(n);
1776 if (outcnt() == 0) { // Above transform() may kill us!
1777 return top;
1778 }
1779 // If transformed to a MergeMem, get the desired slice
1780 // Otherwise the returned node represents memory for every slice
1781 Node *new_mem = (m->is_MergeMem()) ?
1782 m->as_MergeMem()->memory_at(alias_idx) : m;
1783 // Update input if it is progress over what we have now
1784 if (new_mem != ii) {
1785 set_req(i, new_mem);
1786 progress = this;
1787 }
1788 }
1789 }
1790 } else {
1791 // We know that at least one MergeMem->base_memory() == this
1792 // (saw_self == true). If all other inputs also references this phi
1793 // (directly or through data nodes) - it is dead loop.
1794 bool saw_safe_input = false;
1795 for (uint j = 1; j < req(); ++j) {
1796 Node *n = in(j);
1797 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1798 continue; // skip known cases
1799 if (!is_unsafe_data_reference(n)) {
1800 saw_safe_input = true; // found safe input
1801 break;
1802 }
1803 }
1804 if (!saw_safe_input)
1805 return top; // all inputs reference back to this phi - dead loop
1807 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1808 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1809 PhaseIterGVN *igvn = phase->is_IterGVN();
1810 Node* hook = new (phase->C, 1) Node(1);
1811 PhiNode* new_base = (PhiNode*) clone();
1812 // Must eagerly register phis, since they participate in loops.
1813 if (igvn) {
1814 igvn->register_new_node_with_optimizer(new_base);
1815 hook->add_req(new_base);
1816 }
1817 MergeMemNode* result = MergeMemNode::make(phase->C, new_base);
1818 for (uint i = 1; i < req(); ++i) {
1819 Node *ii = in(i);
1820 if (ii->is_MergeMem()) {
1821 MergeMemNode* n = ii->as_MergeMem();
1822 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1823 // If we have not seen this slice yet, make a phi for it.
1824 bool made_new_phi = false;
1825 if (mms.is_empty()) {
1826 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1827 made_new_phi = true;
1828 if (igvn) {
1829 igvn->register_new_node_with_optimizer(new_phi);
1830 hook->add_req(new_phi);
1831 }
1832 mms.set_memory(new_phi);
1833 }
1834 Node* phi = mms.memory();
1835 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1836 phi->set_req(i, mms.memory2());
1837 }
1838 }
1839 }
1840 // Distribute all self-loops.
1841 { // (Extra braces to hide mms.)
1842 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1843 Node* phi = mms.memory();
1844 for (uint i = 1; i < req(); ++i) {
1845 if (phi->in(i) == this) phi->set_req(i, phi);
1846 }
1847 }
1848 }
1849 // now transform the new nodes, and return the mergemem
1850 for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1851 Node* phi = mms.memory();
1852 mms.set_memory(phase->transform(phi));
1853 }
1854 if (igvn) { // Unhook.
1855 igvn->hash_delete(hook);
1856 for (uint i = 1; i < hook->req(); i++) {
1857 hook->set_req(i, NULL);
1858 }
1859 }
1860 // Replace self with the result.
1861 return result;
1862 }
1863 }
1864 //
1865 // Other optimizations on the memory chain
1866 //
1867 const TypePtr* at = adr_type();
1868 for( uint i=1; i<req(); ++i ) {// For all paths in
1869 Node *ii = in(i);
1870 Node *new_in = MemNode::optimize_memory_chain(ii, at, phase);
1871 if (ii != new_in ) {
1872 set_req(i, new_in);
1873 progress = this;
1874 }
1875 }
1876 }
1878 #ifdef _LP64
1879 // Push DecodeN down through phi.
1880 // The rest of phi graph will transform by split EncodeP node though phis up.
1881 if (UseCompressedOops && can_reshape && progress == NULL) {
1882 bool may_push = true;
1883 bool has_decodeN = false;
1884 for (uint i=1; i<req(); ++i) {// For all paths in
1885 Node *ii = in(i);
1886 if (ii->is_DecodeN() && ii->bottom_type() == bottom_type()) {
1887 // Do optimization if a non dead path exist.
1888 if (ii->in(1)->bottom_type() != Type::TOP) {
1889 has_decodeN = true;
1890 }
1891 } else if (!ii->is_Phi()) {
1892 may_push = false;
1893 }
1894 }
1896 if (has_decodeN && may_push) {
1897 PhaseIterGVN *igvn = phase->is_IterGVN();
1898 // Make narrow type for new phi.
1899 const Type* narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
1900 PhiNode* new_phi = new (phase->C, r->req()) PhiNode(r, narrow_t);
1901 uint orig_cnt = req();
1902 for (uint i=1; i<req(); ++i) {// For all paths in
1903 Node *ii = in(i);
1904 Node* new_ii = NULL;
1905 if (ii->is_DecodeN()) {
1906 assert(ii->bottom_type() == bottom_type(), "sanity");
1907 new_ii = ii->in(1);
1908 } else {
1909 assert(ii->is_Phi(), "sanity");
1910 if (ii->as_Phi() == this) {
1911 new_ii = new_phi;
1912 } else {
1913 new_ii = new (phase->C, 2) EncodePNode(ii, narrow_t);
1914 igvn->register_new_node_with_optimizer(new_ii);
1915 }
1916 }
1917 new_phi->set_req(i, new_ii);
1918 }
1919 igvn->register_new_node_with_optimizer(new_phi, this);
1920 progress = new (phase->C, 2) DecodeNNode(new_phi, bottom_type());
1921 }
1922 }
1923 #endif
1925 return progress; // Return any progress
1926 }
1928 //------------------------------is_tripcount-----------------------------------
1929 bool PhiNode::is_tripcount() const {
1930 return (in(0) != NULL && in(0)->is_CountedLoop() &&
1931 in(0)->as_CountedLoop()->phi() == this);
1932 }
1934 //------------------------------out_RegMask------------------------------------
1935 const RegMask &PhiNode::in_RegMask(uint i) const {
1936 return i ? out_RegMask() : RegMask::Empty;
1937 }
1939 const RegMask &PhiNode::out_RegMask() const {
1940 uint ideal_reg = Matcher::base2reg[_type->base()];
1941 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
1942 if( ideal_reg == 0 ) return RegMask::Empty;
1943 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
1944 }
1946 #ifndef PRODUCT
1947 void PhiNode::dump_spec(outputStream *st) const {
1948 TypeNode::dump_spec(st);
1949 if (is_tripcount()) {
1950 st->print(" #tripcount");
1951 }
1952 }
1953 #endif
1956 //=============================================================================
1957 const Type *GotoNode::Value( PhaseTransform *phase ) const {
1958 // If the input is reachable, then we are executed.
1959 // If the input is not reachable, then we are not executed.
1960 return phase->type(in(0));
1961 }
1963 Node *GotoNode::Identity( PhaseTransform *phase ) {
1964 return in(0); // Simple copy of incoming control
1965 }
1967 const RegMask &GotoNode::out_RegMask() const {
1968 return RegMask::Empty;
1969 }
1971 //=============================================================================
1972 const RegMask &JumpNode::out_RegMask() const {
1973 return RegMask::Empty;
1974 }
1976 //=============================================================================
1977 const RegMask &JProjNode::out_RegMask() const {
1978 return RegMask::Empty;
1979 }
1981 //=============================================================================
1982 const RegMask &CProjNode::out_RegMask() const {
1983 return RegMask::Empty;
1984 }
1988 //=============================================================================
1990 uint PCTableNode::hash() const { return Node::hash() + _size; }
1991 uint PCTableNode::cmp( const Node &n ) const
1992 { return _size == ((PCTableNode&)n)._size; }
1994 const Type *PCTableNode::bottom_type() const {
1995 const Type** f = TypeTuple::fields(_size);
1996 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
1997 return TypeTuple::make(_size, f);
1998 }
2000 //------------------------------Value------------------------------------------
2001 // Compute the type of the PCTableNode. If reachable it is a tuple of
2002 // Control, otherwise the table targets are not reachable
2003 const Type *PCTableNode::Value( PhaseTransform *phase ) const {
2004 if( phase->type(in(0)) == Type::CONTROL )
2005 return bottom_type();
2006 return Type::TOP; // All paths dead? Then so are we
2007 }
2009 //------------------------------Ideal------------------------------------------
2010 // Return a node which is more "ideal" than the current node. Strip out
2011 // control copies
2012 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2013 return remove_dead_region(phase, can_reshape) ? this : NULL;
2014 }
2016 //=============================================================================
2017 uint JumpProjNode::hash() const {
2018 return Node::hash() + _dest_bci;
2019 }
2021 uint JumpProjNode::cmp( const Node &n ) const {
2022 return ProjNode::cmp(n) &&
2023 _dest_bci == ((JumpProjNode&)n)._dest_bci;
2024 }
2026 #ifndef PRODUCT
2027 void JumpProjNode::dump_spec(outputStream *st) const {
2028 ProjNode::dump_spec(st);
2029 st->print("@bci %d ",_dest_bci);
2030 }
2031 #endif
2033 //=============================================================================
2034 //------------------------------Value------------------------------------------
2035 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot
2036 // have the default "fall_through_index" path.
2037 const Type *CatchNode::Value( PhaseTransform *phase ) const {
2038 // Unreachable? Then so are all paths from here.
2039 if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2040 // First assume all paths are reachable
2041 const Type** f = TypeTuple::fields(_size);
2042 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2043 // Identify cases that will always throw an exception
2044 // () rethrow call
2045 // () virtual or interface call with NULL receiver
2046 // () call is a check cast with incompatible arguments
2047 if( in(1)->is_Proj() ) {
2048 Node *i10 = in(1)->in(0);
2049 if( i10->is_Call() ) {
2050 CallNode *call = i10->as_Call();
2051 // Rethrows always throw exceptions, never return
2052 if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2053 f[CatchProjNode::fall_through_index] = Type::TOP;
2054 } else if( call->req() > TypeFunc::Parms ) {
2055 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2056 // Check for null receiver to virtual or interface calls
2057 if( call->is_CallDynamicJava() &&
2058 arg0->higher_equal(TypePtr::NULL_PTR) ) {
2059 f[CatchProjNode::fall_through_index] = Type::TOP;
2060 }
2061 } // End of if not a runtime stub
2062 } // End of if have call above me
2063 } // End of slot 1 is not a projection
2064 return TypeTuple::make(_size, f);
2065 }
2067 //=============================================================================
2068 uint CatchProjNode::hash() const {
2069 return Node::hash() + _handler_bci;
2070 }
2073 uint CatchProjNode::cmp( const Node &n ) const {
2074 return ProjNode::cmp(n) &&
2075 _handler_bci == ((CatchProjNode&)n)._handler_bci;
2076 }
2079 //------------------------------Identity---------------------------------------
2080 // If only 1 target is possible, choose it if it is the main control
2081 Node *CatchProjNode::Identity( PhaseTransform *phase ) {
2082 // If my value is control and no other value is, then treat as ID
2083 const TypeTuple *t = phase->type(in(0))->is_tuple();
2084 if (t->field_at(_con) != Type::CONTROL) return this;
2085 // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2086 // also remove any exception table entry. Thus we must know the call
2087 // feeding the Catch will not really throw an exception. This is ok for
2088 // the main fall-thru control (happens when we know a call can never throw
2089 // an exception) or for "rethrow", because a further optimization will
2090 // yank the rethrow (happens when we inline a function that can throw an
2091 // exception and the caller has no handler). Not legal, e.g., for passing
2092 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2093 // These cases MUST throw an exception via the runtime system, so the VM
2094 // will be looking for a table entry.
2095 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode
2096 CallNode *call;
2097 if (_con != TypeFunc::Control && // Bail out if not the main control.
2098 !(proj->is_Proj() && // AND NOT a rethrow
2099 proj->in(0)->is_Call() &&
2100 (call = proj->in(0)->as_Call()) &&
2101 call->entry_point() == OptoRuntime::rethrow_stub()))
2102 return this;
2104 // Search for any other path being control
2105 for (uint i = 0; i < t->cnt(); i++) {
2106 if (i != _con && t->field_at(i) == Type::CONTROL)
2107 return this;
2108 }
2109 // Only my path is possible; I am identity on control to the jump
2110 return in(0)->in(0);
2111 }
2114 #ifndef PRODUCT
2115 void CatchProjNode::dump_spec(outputStream *st) const {
2116 ProjNode::dump_spec(st);
2117 st->print("@bci %d ",_handler_bci);
2118 }
2119 #endif
2121 //=============================================================================
2122 //------------------------------Identity---------------------------------------
2123 // Check for CreateEx being Identity.
2124 Node *CreateExNode::Identity( PhaseTransform *phase ) {
2125 if( phase->type(in(1)) == Type::TOP ) return in(1);
2126 if( phase->type(in(0)) == Type::TOP ) return in(0);
2127 // We only come from CatchProj, unless the CatchProj goes away.
2128 // If the CatchProj is optimized away, then we just carry the
2129 // exception oop through.
2130 CallNode *call = in(1)->in(0)->as_Call();
2132 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2133 ? this
2134 : call->in(TypeFunc::Parms);
2135 }
2137 //=============================================================================
2138 //------------------------------Value------------------------------------------
2139 // Check for being unreachable.
2140 const Type *NeverBranchNode::Value( PhaseTransform *phase ) const {
2141 if (!in(0) || in(0)->is_top()) return Type::TOP;
2142 return bottom_type();
2143 }
2145 //------------------------------Ideal------------------------------------------
2146 // Check for no longer being part of a loop
2147 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2148 if (can_reshape && !in(0)->is_Loop()) {
2149 // Dead code elimination can sometimes delete this projection so
2150 // if it's not there, there's nothing to do.
2151 Node* fallthru = proj_out(0);
2152 if (fallthru != NULL) {
2153 phase->is_IterGVN()->replace_node(fallthru, in(0));
2154 }
2155 return phase->C->top();
2156 }
2157 return NULL;
2158 }
2160 #ifndef PRODUCT
2161 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2162 st->print("%s", Name());
2163 }
2164 #endif