1 /*
2 * Copyright 1997-2005 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Portions of code courtesy of Clifford Click
26
27 // Optimization - Graph Style
28
29 #include "incls/_precompiled.incl"
30 #include "incls/_domgraph.cpp.incl"
31
32 //------------------------------Tarjan-----------------------------------------
33 // A data structure that holds all the information needed to find dominators.
34 struct Tarjan {
35 Block *_block; // Basic block for this info
36
37 uint _semi; // Semi-dominators
38 uint _size; // Used for faster LINK and EVAL
39 Tarjan *_parent; // Parent in DFS
40 Tarjan *_label; // Used for LINK and EVAL
41 Tarjan *_ancestor; // Used for LINK and EVAL
42 Tarjan *_child; // Used for faster LINK and EVAL
43 Tarjan *_dom; // Parent in dominator tree (immediate dom)
44 Tarjan *_bucket; // Set of vertices with given semidominator
45
46 Tarjan *_dom_child; // Child in dominator tree
47 Tarjan *_dom_next; // Next in dominator tree
48
49 // Fast union-find work
50 void COMPRESS();
51 Tarjan *EVAL(void);
52 void LINK( Tarjan *w, Tarjan *tarjan0 );
53
54 void setdepth( uint size );
55
56 };
57
58 //------------------------------Dominator--------------------------------------
59 // Compute the dominator tree of the CFG. The CFG must already have been
60 // constructed. This is the Lengauer & Tarjan O(E-alpha(E,V)) algorithm.
61 void PhaseCFG::Dominators( ) {
62 // Pre-grow the blocks array, prior to the ResourceMark kicking in
63 _blocks.map(_num_blocks,0);
64
65 ResourceMark rm;
66 // Setup mappings from my Graph to Tarjan's stuff and back
67 // Note: Tarjan uses 1-based arrays
68 Tarjan *tarjan = NEW_RESOURCE_ARRAY(Tarjan,_num_blocks+1);
69
70 // Tarjan's algorithm, almost verbatim:
71 // Step 1:
72 _rpo_ctr = _num_blocks;
73 uint dfsnum = DFS( tarjan );
74 if( dfsnum-1 != _num_blocks ) {// Check for unreachable loops!
75 // If the returned dfsnum does not match the number of blocks, then we
76 // must have some unreachable loops. These can be made at any time by
77 // IterGVN. They are cleaned up by CCP or the loop opts, but the last
78 // IterGVN can always make more that are not cleaned up. Highly unlikely
79 // except in ZKM.jar, where endless irreducible loops cause the loop opts
80 // to not get run.
81 //
82 // Having found unreachable loops, we have made a bad RPO _block layout.
83 // We can re-run the above DFS pass with the correct number of blocks,
84 // and hack the Tarjan algorithm below to be robust in the presence of
85 // such dead loops (as was done for the NTarjan code farther below).
86 // Since this situation is so unlikely, instead I've decided to bail out.
87 // CNC 7/24/2001
88 C->record_method_not_compilable("unreachable loop");
89 return;
90 }
91 _blocks._cnt = _num_blocks;
92
93 // Tarjan is using 1-based arrays, so these are some initialize flags
94 tarjan[0]._size = tarjan[0]._semi = 0;
95 tarjan[0]._label = &tarjan[0];
96
97 uint i;
98 for( i=_num_blocks; i>=2; i-- ) { // For all vertices in DFS order
99 Tarjan *w = &tarjan[i]; // Get vertex from DFS
100
101 // Step 2:
102 Node *whead = w->_block->head();
103 for( uint j=1; j < whead->req(); j++ ) {
104 Block *b = _bbs[whead->in(j)->_idx];
105 Tarjan *vx = &tarjan[b->_pre_order];
106 Tarjan *u = vx->EVAL();
107 if( u->_semi < w->_semi )
108 w->_semi = u->_semi;
109 }
110
111 // w is added to a bucket here, and only here.
112 // Thus w is in at most one bucket and the sum of all bucket sizes is O(n).
113 // Thus bucket can be a linked list.
114 // Thus we do not need a small integer name for each Block.
115 w->_bucket = tarjan[w->_semi]._bucket;
116 tarjan[w->_semi]._bucket = w;
117
118 w->_parent->LINK( w, &tarjan[0] );
119
120 // Step 3:
121 for( Tarjan *vx = w->_parent->_bucket; vx; vx = vx->_bucket ) {
122 Tarjan *u = vx->EVAL();
123 vx->_dom = (u->_semi < vx->_semi) ? u : w->_parent;
124 }
125 }
126
127 // Step 4:
128 for( i=2; i <= _num_blocks; i++ ) {
129 Tarjan *w = &tarjan[i];
130 if( w->_dom != &tarjan[w->_semi] )
131 w->_dom = w->_dom->_dom;
132 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later
133 }
134 // No immediate dominator for the root
135 Tarjan *w = &tarjan[_broot->_pre_order];
136 w->_dom = NULL;
137 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later
138
139 // Convert the dominator tree array into my kind of graph
140 for( i=1; i<=_num_blocks;i++){// For all Tarjan vertices
141 Tarjan *t = &tarjan[i]; // Handy access
142 Tarjan *tdom = t->_dom; // Handy access to immediate dominator
143 if( tdom ) { // Root has no immediate dominator
144 t->_block->_idom = tdom->_block; // Set immediate dominator
145 t->_dom_next = tdom->_dom_child; // Make me a sibling of parent's child
146 tdom->_dom_child = t; // Make me a child of my parent
147 } else
148 t->_block->_idom = NULL; // Root
149 }
150 w->setdepth( _num_blocks+1 ); // Set depth in dominator tree
151
152 }
153
154 //----------------------------Block_Stack--------------------------------------
155 class Block_Stack {
156 private:
157 struct Block_Descr {
158 Block *block; // Block
159 int index; // Index of block's successor pushed on stack
160 int freq_idx; // Index of block's most frequent successor
161 };
162 Block_Descr *_stack_top;
163 Block_Descr *_stack_max;
164 Block_Descr *_stack;
165 Tarjan *_tarjan;
166 uint most_frequent_successor( Block *b );
167 public:
168 Block_Stack(Tarjan *tarjan, int size) : _tarjan(tarjan) {
169 _stack = NEW_RESOURCE_ARRAY(Block_Descr, size);
170 _stack_max = _stack + size;
171 _stack_top = _stack - 1; // stack is empty
172 }
173 void push(uint pre_order, Block *b) {
174 Tarjan *t = &_tarjan[pre_order]; // Fast local access
175 b->_pre_order = pre_order; // Flag as visited
176 t->_block = b; // Save actual block
177 t->_semi = pre_order; // Block to DFS map
178 t->_label = t; // DFS to vertex map
179 t->_ancestor = NULL; // Fast LINK & EVAL setup
180 t->_child = &_tarjan[0]; // Sentenial
181 t->_size = 1;
182 t->_bucket = NULL;
183 if (pre_order == 1)
184 t->_parent = NULL; // first block doesn't have parent
185 else {
186 // Save parent (current top block on stack) in DFS
187 t->_parent = &_tarjan[_stack_top->block->_pre_order];
188 }
189 // Now put this block on stack
190 ++_stack_top;
191 assert(_stack_top < _stack_max, ""); // assert if stack have to grow
192 _stack_top->block = b;
193 _stack_top->index = -1;
194 // Find the index into b->succs[] array of the most frequent successor.
195 _stack_top->freq_idx = most_frequent_successor(b); // freq_idx >= 0
196 }
197 Block* pop() { Block* b = _stack_top->block; _stack_top--; return b; }
198 bool is_nonempty() { return (_stack_top >= _stack); }
199 bool last_successor() { return (_stack_top->index == _stack_top->freq_idx); }
200 Block* next_successor() {
201 int i = _stack_top->index;
202 i++;
203 if (i == _stack_top->freq_idx) i++;
204 if (i >= (int)(_stack_top->block->_num_succs)) {
205 i = _stack_top->freq_idx; // process most frequent successor last
206 }
207 _stack_top->index = i;
208 return _stack_top->block->_succs[ i ];
209 }
210 };
211
212 //-------------------------most_frequent_successor-----------------------------
213 // Find the index into the b->succs[] array of the most frequent successor.
214 uint Block_Stack::most_frequent_successor( Block *b ) {
215 uint freq_idx = 0;
216 int eidx = b->end_idx();
217 Node *n = b->_nodes[eidx];
218 int op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode();
219 switch( op ) {
220 case Op_CountedLoopEnd:
221 case Op_If: { // Split frequency amongst children
222 float prob = n->as_MachIf()->_prob;
223 // Is succ[0] the TRUE branch or the FALSE branch?
224 if( b->_nodes[eidx+1]->Opcode() == Op_IfFalse )
225 prob = 1.0f - prob;
226 freq_idx = prob < PROB_FAIR; // freq=1 for succ[0] < 0.5 prob
227 break;
228 }
229 case Op_Catch: // Split frequency amongst children
230 for( freq_idx = 0; freq_idx < b->_num_succs; freq_idx++ )
231 if( b->_nodes[eidx+1+freq_idx]->as_CatchProj()->_con == CatchProjNode::fall_through_index )
232 break;
233 // Handle case of no fall-thru (e.g., check-cast MUST throw an exception)
234 if( freq_idx == b->_num_succs ) freq_idx = 0;
235 break;
236 // Currently there is no support for finding out the most
237 // frequent successor for jumps, so lets just make it the first one
238 case Op_Jump:
239 case Op_Root:
240 case Op_Goto:
241 case Op_NeverBranch:
242 freq_idx = 0; // fall thru
243 break;
244 case Op_TailCall:
245 case Op_TailJump:
246 case Op_Return:
247 case Op_Halt:
248 case Op_Rethrow:
249 break;
250 default:
251 ShouldNotReachHere();
252 }
253 return freq_idx;
254 }
255
256 //------------------------------DFS--------------------------------------------
257 // Perform DFS search. Setup 'vertex' as DFS to vertex mapping. Setup
258 // 'semi' as vertex to DFS mapping. Set 'parent' to DFS parent.
259 uint PhaseCFG::DFS( Tarjan *tarjan ) {
260 Block *b = _broot;
261 uint pre_order = 1;
262 // Allocate stack of size _num_blocks+1 to avoid frequent realloc
263 Block_Stack bstack(tarjan, _num_blocks+1);
264
265 // Push on stack the state for the first block
266 bstack.push(pre_order, b);
267 ++pre_order;
268
269 while (bstack.is_nonempty()) {
270 if (!bstack.last_successor()) {
271 // Walk over all successors in pre-order (DFS).
272 Block *s = bstack.next_successor();
273 if (s->_pre_order == 0) { // Check for no-pre-order, not-visited
274 // Push on stack the state of successor
275 bstack.push(pre_order, s);
276 ++pre_order;
277 }
278 }
279 else {
280 // Build a reverse post-order in the CFG _blocks array
281 Block *stack_top = bstack.pop();
282 stack_top->_rpo = --_rpo_ctr;
283 _blocks.map(stack_top->_rpo, stack_top);
284 }
285 }
286 return pre_order;
287 }
288
289 //------------------------------COMPRESS---------------------------------------
290 void Tarjan::COMPRESS()
291 {
292 assert( _ancestor != 0, "" );
293 if( _ancestor->_ancestor != 0 ) {
294 _ancestor->COMPRESS( );
295 if( _ancestor->_label->_semi < _label->_semi )
296 _label = _ancestor->_label;
297 _ancestor = _ancestor->_ancestor;
298 }
299 }
300
301 //------------------------------EVAL-------------------------------------------
302 Tarjan *Tarjan::EVAL() {
303 if( !_ancestor ) return _label;
304 COMPRESS();
305 return (_ancestor->_label->_semi >= _label->_semi) ? _label : _ancestor->_label;
306 }
307
308 //------------------------------LINK-------------------------------------------
309 void Tarjan::LINK( Tarjan *w, Tarjan *tarjan0 ) {
310 Tarjan *s = w;
311 while( w->_label->_semi < s->_child->_label->_semi ) {
312 if( s->_size + s->_child->_child->_size >= (s->_child->_size << 1) ) {
313 s->_child->_ancestor = s;
314 s->_child = s->_child->_child;
315 } else {
316 s->_child->_size = s->_size;
317 s = s->_ancestor = s->_child;
318 }
319 }
320 s->_label = w->_label;
321 _size += w->_size;
322 if( _size < (w->_size << 1) ) {
323 Tarjan *tmp = s; s = _child; _child = tmp;
324 }
325 while( s != tarjan0 ) {
326 s->_ancestor = this;
327 s = s->_child;
328 }
329 }
330
331 //------------------------------setdepth---------------------------------------
332 void Tarjan::setdepth( uint stack_size ) {
333 Tarjan **top = NEW_RESOURCE_ARRAY(Tarjan*, stack_size);
334 Tarjan **next = top;
335 Tarjan **last;
336 uint depth = 0;
337 *top = this;
338 ++top;
339 do {
340 // next level
341 ++depth;
342 last = top;
343 do {
344 // Set current depth for all tarjans on this level
345 Tarjan *t = *next; // next tarjan from stack
346 ++next;
347 do {
348 t->_block->_dom_depth = depth; // Set depth in dominator tree
349 Tarjan *dom_child = t->_dom_child;
350 t = t->_dom_next; // next tarjan
351 if (dom_child != NULL) {
352 *top = dom_child; // save child on stack
353 ++top;
354 }
355 } while (t != NULL);
356 } while (next < last);
357 } while (last < top);
358 }
359
360 //*********************** DOMINATORS ON THE SEA OF NODES***********************
361 //------------------------------NTarjan----------------------------------------
362 // A data structure that holds all the information needed to find dominators.
363 struct NTarjan {
364 Node *_control; // Control node associated with this info
365
366 uint _semi; // Semi-dominators
367 uint _size; // Used for faster LINK and EVAL
368 NTarjan *_parent; // Parent in DFS
369 NTarjan *_label; // Used for LINK and EVAL
370 NTarjan *_ancestor; // Used for LINK and EVAL
371 NTarjan *_child; // Used for faster LINK and EVAL
372 NTarjan *_dom; // Parent in dominator tree (immediate dom)
373 NTarjan *_bucket; // Set of vertices with given semidominator
374
375 NTarjan *_dom_child; // Child in dominator tree
376 NTarjan *_dom_next; // Next in dominator tree
377
378 // Perform DFS search.
379 // Setup 'vertex' as DFS to vertex mapping.
380 // Setup 'semi' as vertex to DFS mapping.
381 // Set 'parent' to DFS parent.
382 static int DFS( NTarjan *ntarjan, VectorSet &visited, PhaseIdealLoop *pil, uint *dfsorder );
383 void setdepth( uint size, uint *dom_depth );
384
385 // Fast union-find work
386 void COMPRESS();
387 NTarjan *EVAL(void);
388 void LINK( NTarjan *w, NTarjan *ntarjan0 );
389 #ifndef PRODUCT
390 void dump(int offset) const;
391 #endif
392 };
393
394 //------------------------------Dominator--------------------------------------
395 // Compute the dominator tree of the sea of nodes. This version walks all CFG
396 // nodes (using the is_CFG() call) and places them in a dominator tree. Thus,
397 // it needs a count of the CFG nodes for the mapping table. This is the
398 // Lengauer & Tarjan O(E-alpha(E,V)) algorithm.
399 void PhaseIdealLoop::Dominators() {
400 ResourceMark rm;
401 // Setup mappings from my Graph to Tarjan's stuff and back
402 // Note: Tarjan uses 1-based arrays
403 NTarjan *ntarjan = NEW_RESOURCE_ARRAY(NTarjan,C->unique()+1);
404 // Initialize _control field for fast reference
405 int i;
406 for( i= C->unique()-1; i>=0; i-- )
407 ntarjan[i]._control = NULL;
408
409 // Store the DFS order for the main loop
410 uint *dfsorder = NEW_RESOURCE_ARRAY(uint,C->unique()+1);
411 memset(dfsorder, max_uint, (C->unique()+1) * sizeof(uint));
412
413 // Tarjan's algorithm, almost verbatim:
414 // Step 1:
415 VectorSet visited(Thread::current()->resource_area());
416 int dfsnum = NTarjan::DFS( ntarjan, visited, this, dfsorder);
417
418 // Tarjan is using 1-based arrays, so these are some initialize flags
419 ntarjan[0]._size = ntarjan[0]._semi = 0;
420 ntarjan[0]._label = &ntarjan[0];
421
422 for( i = dfsnum-1; i>1; i-- ) { // For all nodes in reverse DFS order
423 NTarjan *w = &ntarjan[i]; // Get Node from DFS
424 assert(w->_control != NULL,"bad DFS walk");
425
426 // Step 2:
427 Node *whead = w->_control;
428 for( uint j=0; j < whead->req(); j++ ) { // For each predecessor
429 if( whead->in(j) == NULL || !whead->in(j)->is_CFG() )
430 continue; // Only process control nodes
431 uint b = dfsorder[whead->in(j)->_idx];
432 if(b == max_uint) continue;
433 NTarjan *vx = &ntarjan[b];
434 NTarjan *u = vx->EVAL();
435 if( u->_semi < w->_semi )
436 w->_semi = u->_semi;
437 }
438
439 // w is added to a bucket here, and only here.
440 // Thus w is in at most one bucket and the sum of all bucket sizes is O(n).
441 // Thus bucket can be a linked list.
442 w->_bucket = ntarjan[w->_semi]._bucket;
443 ntarjan[w->_semi]._bucket = w;
444
445 w->_parent->LINK( w, &ntarjan[0] );
446
447 // Step 3:
448 for( NTarjan *vx = w->_parent->_bucket; vx; vx = vx->_bucket ) {
449 NTarjan *u = vx->EVAL();
450 vx->_dom = (u->_semi < vx->_semi) ? u : w->_parent;
451 }
452
453 // Cleanup any unreachable loops now. Unreachable loops are loops that
454 // flow into the main graph (and hence into ROOT) but are not reachable
455 // from above. Such code is dead, but requires a global pass to detect
456 // it; this global pass was the 'build_loop_tree' pass run just prior.
457 if( !_verify_only && whead->is_Region() ) {
458 for( uint i = 1; i < whead->req(); i++ ) {
459 if (!has_node(whead->in(i))) {
460 // Kill dead input path
461 assert( !visited.test(whead->in(i)->_idx),
462 "input with no loop must be dead" );
463 _igvn.hash_delete(whead);
464 whead->del_req(i);
465 _igvn._worklist.push(whead);
466 for (DUIterator_Fast jmax, j = whead->fast_outs(jmax); j < jmax; j++) {
467 Node* p = whead->fast_out(j);
468 if( p->is_Phi() ) {
469 _igvn.hash_delete(p);
470 p->del_req(i);
471 _igvn._worklist.push(p);
472 }
473 }
474 i--; // Rerun same iteration
475 } // End of if dead input path
476 } // End of for all input paths
477 } // End if if whead is a Region
478 } // End of for all Nodes in reverse DFS order
479
480 // Step 4:
481 for( i=2; i < dfsnum; i++ ) { // DFS order
482 NTarjan *w = &ntarjan[i];
483 assert(w->_control != NULL,"Bad DFS walk");
484 if( w->_dom != &ntarjan[w->_semi] )
485 w->_dom = w->_dom->_dom;
486 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later
487 }
488 // No immediate dominator for the root
489 NTarjan *w = &ntarjan[dfsorder[C->root()->_idx]];
490 w->_dom = NULL;
491 w->_parent = NULL;
492 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later
493
494 // Convert the dominator tree array into my kind of graph
495 for( i=1; i<dfsnum; i++ ) { // For all Tarjan vertices
496 NTarjan *t = &ntarjan[i]; // Handy access
497 assert(t->_control != NULL,"Bad DFS walk");
498 NTarjan *tdom = t->_dom; // Handy access to immediate dominator
499 if( tdom ) { // Root has no immediate dominator
500 _idom[t->_control->_idx] = tdom->_control; // Set immediate dominator
501 t->_dom_next = tdom->_dom_child; // Make me a sibling of parent's child
502 tdom->_dom_child = t; // Make me a child of my parent
503 } else
504 _idom[C->root()->_idx] = NULL; // Root
505 }
506 w->setdepth( C->unique()+1, _dom_depth ); // Set depth in dominator tree
507 // Pick up the 'top' node as well
508 _idom [C->top()->_idx] = C->root();
509 _dom_depth[C->top()->_idx] = 1;
510
511 // Debug Print of Dominator tree
512 if( PrintDominators ) {
513 #ifndef PRODUCT
514 w->dump(0);
515 #endif
516 }
517 }
518
519 //------------------------------DFS--------------------------------------------
520 // Perform DFS search. Setup 'vertex' as DFS to vertex mapping. Setup
521 // 'semi' as vertex to DFS mapping. Set 'parent' to DFS parent.
522 int NTarjan::DFS( NTarjan *ntarjan, VectorSet &visited, PhaseIdealLoop *pil, uint *dfsorder) {
523 // Allocate stack of size C->unique()/8 to avoid frequent realloc
524 GrowableArray <Node *> dfstack(pil->C->unique() >> 3);
525 Node *b = pil->C->root();
526 int dfsnum = 1;
527 dfsorder[b->_idx] = dfsnum; // Cache parent's dfsnum for a later use
528 dfstack.push(b);
529
530 while (dfstack.is_nonempty()) {
531 b = dfstack.pop();
532 if( !visited.test_set(b->_idx) ) { // Test node and flag it as visited
533 NTarjan *w = &ntarjan[dfsnum];
534 // Only fully process control nodes
535 w->_control = b; // Save actual node
536 // Use parent's cached dfsnum to identify "Parent in DFS"
537 w->_parent = &ntarjan[dfsorder[b->_idx]];
538 dfsorder[b->_idx] = dfsnum; // Save DFS order info
539 w->_semi = dfsnum; // Node to DFS map
540 w->_label = w; // DFS to vertex map
541 w->_ancestor = NULL; // Fast LINK & EVAL setup
542 w->_child = &ntarjan[0]; // Sentinal
543 w->_size = 1;
544 w->_bucket = NULL;
545
546 // Need DEF-USE info for this pass
547 for ( int i = b->outcnt(); i-- > 0; ) { // Put on stack backwards
548 Node* s = b->raw_out(i); // Get a use
549 // CFG nodes only and not dead stuff
550 if( s->is_CFG() && pil->has_node(s) && !visited.test(s->_idx) ) {
551 dfsorder[s->_idx] = dfsnum; // Cache parent's dfsnum for a later use
552 dfstack.push(s);
553 }
554 }
555 dfsnum++; // update after parent's dfsnum has been cached.
556 }
557 }
558
559 return dfsnum;
560 }
561
562 //------------------------------COMPRESS---------------------------------------
563 void NTarjan::COMPRESS()
564 {
565 assert( _ancestor != 0, "" );
566 if( _ancestor->_ancestor != 0 ) {
567 _ancestor->COMPRESS( );
568 if( _ancestor->_label->_semi < _label->_semi )
569 _label = _ancestor->_label;
570 _ancestor = _ancestor->_ancestor;
571 }
572 }
573
574 //------------------------------EVAL-------------------------------------------
575 NTarjan *NTarjan::EVAL() {
576 if( !_ancestor ) return _label;
577 COMPRESS();
578 return (_ancestor->_label->_semi >= _label->_semi) ? _label : _ancestor->_label;
579 }
580
581 //------------------------------LINK-------------------------------------------
582 void NTarjan::LINK( NTarjan *w, NTarjan *ntarjan0 ) {
583 NTarjan *s = w;
584 while( w->_label->_semi < s->_child->_label->_semi ) {
585 if( s->_size + s->_child->_child->_size >= (s->_child->_size << 1) ) {
586 s->_child->_ancestor = s;
587 s->_child = s->_child->_child;
588 } else {
589 s->_child->_size = s->_size;
590 s = s->_ancestor = s->_child;
591 }
592 }
593 s->_label = w->_label;
594 _size += w->_size;
595 if( _size < (w->_size << 1) ) {
596 NTarjan *tmp = s; s = _child; _child = tmp;
597 }
598 while( s != ntarjan0 ) {
599 s->_ancestor = this;
600 s = s->_child;
601 }
602 }
603
604 //------------------------------setdepth---------------------------------------
605 void NTarjan::setdepth( uint stack_size, uint *dom_depth ) {
606 NTarjan **top = NEW_RESOURCE_ARRAY(NTarjan*, stack_size);
607 NTarjan **next = top;
608 NTarjan **last;
609 uint depth = 0;
610 *top = this;
611 ++top;
612 do {
613 // next level
614 ++depth;
615 last = top;
616 do {
617 // Set current depth for all tarjans on this level
618 NTarjan *t = *next; // next tarjan from stack
619 ++next;
620 do {
621 dom_depth[t->_control->_idx] = depth; // Set depth in dominator tree
622 NTarjan *dom_child = t->_dom_child;
623 t = t->_dom_next; // next tarjan
624 if (dom_child != NULL) {
625 *top = dom_child; // save child on stack
626 ++top;
627 }
628 } while (t != NULL);
629 } while (next < last);
630 } while (last < top);
631 }
632
633 //------------------------------dump-------------------------------------------
634 #ifndef PRODUCT
635 void NTarjan::dump(int offset) const {
636 // Dump the data from this node
637 int i;
638 for(i = offset; i >0; i--) // Use indenting for tree structure
639 tty->print(" ");
640 tty->print("Dominator Node: ");
641 _control->dump(); // Control node for this dom node
642 tty->print("\n");
643 for(i = offset; i >0; i--) // Use indenting for tree structure
644 tty->print(" ");
645 tty->print("semi:%d, size:%d\n",_semi, _size);
646 for(i = offset; i >0; i--) // Use indenting for tree structure
647 tty->print(" ");
648 tty->print("DFS Parent: ");
649 if(_parent != NULL)
650 _parent->_control->dump(); // Parent in DFS
651 tty->print("\n");
652 for(i = offset; i >0; i--) // Use indenting for tree structure
653 tty->print(" ");
654 tty->print("Dom Parent: ");
655 if(_dom != NULL)
656 _dom->_control->dump(); // Parent in Dominator Tree
657 tty->print("\n");
658
659 // Recurse over remaining tree
660 if( _dom_child ) _dom_child->dump(offset+2); // Children in dominator tree
661 if( _dom_next ) _dom_next ->dump(offset ); // Siblings in dominator tree
662
663 }
664 #endif