1/*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25#include "precompiled.hpp"
26#include "libadt/vectset.hpp"
27#include "memory/allocation.hpp"
28#include "memory/resourceArea.hpp"
29#include "opto/block.hpp"
30#include "opto/machnode.hpp"
31#include "opto/phaseX.hpp"
32#include "opto/rootnode.hpp"
33
34// Portions of code courtesy of Clifford Click
35
36// A data structure that holds all the information needed to find dominators.
37struct Tarjan {
38 Block *_block; // Basic block for this info
39
40 uint _semi; // Semi-dominators
41 uint _size; // Used for faster LINK and EVAL
42 Tarjan *_parent; // Parent in DFS
43 Tarjan *_label; // Used for LINK and EVAL
44 Tarjan *_ancestor; // Used for LINK and EVAL
45 Tarjan *_child; // Used for faster LINK and EVAL
46 Tarjan *_dom; // Parent in dominator tree (immediate dom)
47 Tarjan *_bucket; // Set of vertices with given semidominator
48
49 Tarjan *_dom_child; // Child in dominator tree
50 Tarjan *_dom_next; // Next in dominator tree
51
52 // Fast union-find work
53 void COMPRESS();
54 Tarjan *EVAL(void);
55 void LINK( Tarjan *w, Tarjan *tarjan0 );
56
57 void setdepth( uint size );
58
59};
60
61// Compute the dominator tree of the CFG. The CFG must already have been
62// constructed. This is the Lengauer & Tarjan O(E-alpha(E,V)) algorithm.
63void PhaseCFG::build_dominator_tree() {
64 // Pre-grow the blocks array, prior to the ResourceMark kicking in
65 _blocks.map(number_of_blocks(), 0);
66
67 ResourceMark rm;
68 // Setup mappings from my Graph to Tarjan's stuff and back
69 // Note: Tarjan uses 1-based arrays
70 Tarjan* tarjan = NEW_RESOURCE_ARRAY(Tarjan, number_of_blocks() + 1);
71
72 // Tarjan's algorithm, almost verbatim:
73 // Step 1:
74 uint dfsnum = do_DFS(tarjan, number_of_blocks());
75 if (dfsnum - 1 != number_of_blocks()) { // Check for unreachable loops!
76 // If the returned dfsnum does not match the number of blocks, then we
77 // must have some unreachable loops. These can be made at any time by
78 // IterGVN. They are cleaned up by CCP or the loop opts, but the last
79 // IterGVN can always make more that are not cleaned up. Highly unlikely
80 // except in ZKM.jar, where endless irreducible loops cause the loop opts
81 // to not get run.
82 //
83 // Having found unreachable loops, we have made a bad RPO _block layout.
84 // We can re-run the above DFS pass with the correct number of blocks,
85 // and hack the Tarjan algorithm below to be robust in the presence of
86 // such dead loops (as was done for the NTarjan code farther below).
87 // Since this situation is so unlikely, instead I've decided to bail out.
88 // CNC 7/24/2001
89 C->record_method_not_compilable("unreachable loop");
90 return;
91 }
92 _blocks._cnt = number_of_blocks();
93
94 // Tarjan is using 1-based arrays, so these are some initialize flags
95 tarjan[0]._size = tarjan[0]._semi = 0;
96 tarjan[0]._label = &tarjan[0];
97
98 for (uint i = number_of_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 = get_block_for_node(whead->in(j));
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 (uint i = 2; i <= number_of_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[get_root_block()->_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(uint i = 1; i <= number_of_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(number_of_blocks() + 1); // Set depth in dominator tree
151
152}
153
154class Block_Stack {
155 private:
156 struct Block_Descr {
157 Block *block; // Block
158 int index; // Index of block's successor pushed on stack
159 int freq_idx; // Index of block's most frequent successor
160 };
161 Block_Descr *_stack_top;
162 Block_Descr *_stack_max;
163 Block_Descr *_stack;
164 Tarjan *_tarjan;
165 uint most_frequent_successor( Block *b );
166 public:
167 Block_Stack(Tarjan *tarjan, int size) : _tarjan(tarjan) {
168 _stack = NEW_RESOURCE_ARRAY(Block_Descr, size);
169 _stack_max = _stack + size;
170 _stack_top = _stack - 1; // stack is empty
171 }
172 void push(uint pre_order, Block *b) {
173 Tarjan *t = &_tarjan[pre_order]; // Fast local access
174 b->_pre_order = pre_order; // Flag as visited
175 t->_block = b; // Save actual block
176 t->_semi = pre_order; // Block to DFS map
177 t->_label = t; // DFS to vertex map
178 t->_ancestor = NULL; // Fast LINK & EVAL setup
179 t->_child = &_tarjan[0]; // Sentenial
180 t->_size = 1;
181 t->_bucket = NULL;
182 if (pre_order == 1)
183 t->_parent = NULL; // first block doesn't have parent
184 else {
185 // Save parent (current top block on stack) in DFS
186 t->_parent = &_tarjan[_stack_top->block->_pre_order];
187 }
188 // Now put this block on stack
189 ++_stack_top;
190 assert(_stack_top < _stack_max, ""); // assert if stack have to grow
191 _stack_top->block = b;
192 _stack_top->index = -1;
193 // Find the index into b->succs[] array of the most frequent successor.
194 _stack_top->freq_idx = most_frequent_successor(b); // freq_idx >= 0
195 }
196 Block* pop() { Block* b = _stack_top->block; _stack_top--; return b; }
197 bool is_nonempty() { return (_stack_top >= _stack); }
198 bool last_successor() { return (_stack_top->index == _stack_top->freq_idx); }
199 Block* next_successor() {
200 int i = _stack_top->index;
201 i++;
202 if (i == _stack_top->freq_idx) i++;
203 if (i >= (int)(_stack_top->block->_num_succs)) {
204 i = _stack_top->freq_idx; // process most frequent successor last
205 }
206 _stack_top->index = i;
207 return _stack_top->block->_succs[ i ];
208 }
209};
210
211// Find the index into the b->succs[] array of the most frequent successor.
212uint Block_Stack::most_frequent_successor( Block *b ) {
213 uint freq_idx = 0;
214 int eidx = b->end_idx();
215 Node *n = b->get_node(eidx);
216 int op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode();
217 switch( op ) {
218 case Op_CountedLoopEnd:
219 case Op_If: { // Split frequency amongst children
220 float prob = n->as_MachIf()->_prob;
221 // Is succ[0] the TRUE branch or the FALSE branch?
222 if( b->get_node(eidx+1)->Opcode() == Op_IfFalse )
223 prob = 1.0f - prob;
224 freq_idx = prob < PROB_FAIR; // freq=1 for succ[0] < 0.5 prob
225 break;
226 }
227 case Op_Catch: // Split frequency amongst children
228 for( freq_idx = 0; freq_idx < b->_num_succs; freq_idx++ )
229 if( b->get_node(eidx+1+freq_idx)->as_CatchProj()->_con == CatchProjNode::fall_through_index )
230 break;
231 // Handle case of no fall-thru (e.g., check-cast MUST throw an exception)
232 if( freq_idx == b->_num_succs ) freq_idx = 0;
233 break;
234 // Currently there is no support for finding out the most
235 // frequent successor for jumps, so lets just make it the first one
236 case Op_Jump:
237 case Op_Root:
238 case Op_Goto:
239 case Op_NeverBranch:
240 freq_idx = 0; // fall thru
241 break;
242 case Op_TailCall:
243 case Op_TailJump:
244 case Op_Return:
245 case Op_Halt:
246 case Op_Rethrow:
247 break;
248 default:
249 ShouldNotReachHere();
250 }
251 return freq_idx;
252}
253
254// Perform DFS search. Setup 'vertex' as DFS to vertex mapping. Setup
255// 'semi' as vertex to DFS mapping. Set 'parent' to DFS parent.
256uint PhaseCFG::do_DFS(Tarjan *tarjan, uint rpo_counter) {
257 Block* root_block = get_root_block();
258 uint pre_order = 1;
259 // Allocate stack of size number_of_blocks() + 1 to avoid frequent realloc
260 Block_Stack bstack(tarjan, number_of_blocks() + 1);
261
262 // Push on stack the state for the first block
263 bstack.push(pre_order, root_block);
264 ++pre_order;
265
266 while (bstack.is_nonempty()) {
267 if (!bstack.last_successor()) {
268 // Walk over all successors in pre-order (DFS).
269 Block* next_block = bstack.next_successor();
270 if (next_block->_pre_order == 0) { // Check for no-pre-order, not-visited
271 // Push on stack the state of successor
272 bstack.push(pre_order, next_block);
273 ++pre_order;
274 }
275 }
276 else {
277 // Build a reverse post-order in the CFG _blocks array
278 Block *stack_top = bstack.pop();
279 stack_top->_rpo = --rpo_counter;
280 _blocks.map(stack_top->_rpo, stack_top);
281 }
282 }
283 return pre_order;
284}
285
286void Tarjan::COMPRESS()
287{
288 assert( _ancestor != 0, "" );
289 if( _ancestor->_ancestor != 0 ) {
290 _ancestor->COMPRESS( );
291 if( _ancestor->_label->_semi < _label->_semi )
292 _label = _ancestor->_label;
293 _ancestor = _ancestor->_ancestor;
294 }
295}
296
297Tarjan *Tarjan::EVAL() {
298 if( !_ancestor ) return _label;
299 COMPRESS();
300 return (_ancestor->_label->_semi >= _label->_semi) ? _label : _ancestor->_label;
301}
302
303void Tarjan::LINK( Tarjan *w, Tarjan *tarjan0 ) {
304 Tarjan *s = w;
305 while( w->_label->_semi < s->_child->_label->_semi ) {
306 if( s->_size + s->_child->_child->_size >= (s->_child->_size << 1) ) {
307 s->_child->_ancestor = s;
308 s->_child = s->_child->_child;
309 } else {
310 s->_child->_size = s->_size;
311 s = s->_ancestor = s->_child;
312 }
313 }
314 s->_label = w->_label;
315 _size += w->_size;
316 if( _size < (w->_size << 1) ) {
317 Tarjan *tmp = s; s = _child; _child = tmp;
318 }
319 while( s != tarjan0 ) {
320 s->_ancestor = this;
321 s = s->_child;
322 }
323}
324
325void Tarjan::setdepth( uint stack_size ) {
326 Tarjan **top = NEW_RESOURCE_ARRAY(Tarjan*, stack_size);
327 Tarjan **next = top;
328 Tarjan **last;
329 uint depth = 0;
330 *top = this;
331 ++top;
332 do {
333 // next level
334 ++depth;
335 last = top;
336 do {
337 // Set current depth for all tarjans on this level
338 Tarjan *t = *next; // next tarjan from stack
339 ++next;
340 do {
341 t->_block->_dom_depth = depth; // Set depth in dominator tree
342 Tarjan *dom_child = t->_dom_child;
343 t = t->_dom_next; // next tarjan
344 if (dom_child != NULL) {
345 *top = dom_child; // save child on stack
346 ++top;
347 }
348 } while (t != NULL);
349 } while (next < last);
350 } while (last < top);
351}
352
353// Compute dominators on the Sea of Nodes form
354// A data structure that holds all the information needed to find dominators.
355struct NTarjan {
356 Node *_control; // Control node associated with this info
357
358 uint _semi; // Semi-dominators
359 uint _size; // Used for faster LINK and EVAL
360 NTarjan *_parent; // Parent in DFS
361 NTarjan *_label; // Used for LINK and EVAL
362 NTarjan *_ancestor; // Used for LINK and EVAL
363 NTarjan *_child; // Used for faster LINK and EVAL
364 NTarjan *_dom; // Parent in dominator tree (immediate dom)
365 NTarjan *_bucket; // Set of vertices with given semidominator
366
367 NTarjan *_dom_child; // Child in dominator tree
368 NTarjan *_dom_next; // Next in dominator tree
369
370 // Perform DFS search.
371 // Setup 'vertex' as DFS to vertex mapping.
372 // Setup 'semi' as vertex to DFS mapping.
373 // Set 'parent' to DFS parent.
374 static int DFS( NTarjan *ntarjan, VectorSet &visited, PhaseIdealLoop *pil, uint *dfsorder );
375 void setdepth( uint size, uint *dom_depth );
376
377 // Fast union-find work
378 void COMPRESS();
379 NTarjan *EVAL(void);
380 void LINK( NTarjan *w, NTarjan *ntarjan0 );
381#ifndef PRODUCT
382 void dump(int offset) const;
383#endif
384};
385
386// Compute the dominator tree of the sea of nodes. This version walks all CFG
387// nodes (using the is_CFG() call) and places them in a dominator tree. Thus,
388// it needs a count of the CFG nodes for the mapping table. This is the
389// Lengauer & Tarjan O(E-alpha(E,V)) algorithm.
390void PhaseIdealLoop::Dominators() {
391 ResourceMark rm;
392 // Setup mappings from my Graph to Tarjan's stuff and back
393 // Note: Tarjan uses 1-based arrays
394 NTarjan *ntarjan = NEW_RESOURCE_ARRAY(NTarjan,C->unique()+1);
395 // Initialize _control field for fast reference
396 int i;
397 for( i= C->unique()-1; i>=0; i-- )
398 ntarjan[i]._control = NULL;
399
400 // Store the DFS order for the main loop
401 const uint fill_value = max_juint;
402 uint *dfsorder = NEW_RESOURCE_ARRAY(uint,C->unique()+1);
403 memset(dfsorder, fill_value, (C->unique()+1) * sizeof(uint));
404
405 // Tarjan's algorithm, almost verbatim:
406 // Step 1:
407 VectorSet visited(Thread::current()->resource_area());
408 int dfsnum = NTarjan::DFS( ntarjan, visited, this, dfsorder);
409
410 // Tarjan is using 1-based arrays, so these are some initialize flags
411 ntarjan[0]._size = ntarjan[0]._semi = 0;
412 ntarjan[0]._label = &ntarjan[0];
413
414 for( i = dfsnum-1; i>1; i-- ) { // For all nodes in reverse DFS order
415 NTarjan *w = &ntarjan[i]; // Get Node from DFS
416 assert(w->_control != NULL,"bad DFS walk");
417
418 // Step 2:
419 Node *whead = w->_control;
420 for( uint j=0; j < whead->req(); j++ ) { // For each predecessor
421 if( whead->in(j) == NULL || !whead->in(j)->is_CFG() )
422 continue; // Only process control nodes
423 uint b = dfsorder[whead->in(j)->_idx];
424 if(b == fill_value) continue;
425 NTarjan *vx = &ntarjan[b];
426 NTarjan *u = vx->EVAL();
427 if( u->_semi < w->_semi )
428 w->_semi = u->_semi;
429 }
430
431 // w is added to a bucket here, and only here.
432 // Thus w is in at most one bucket and the sum of all bucket sizes is O(n).
433 // Thus bucket can be a linked list.
434 w->_bucket = ntarjan[w->_semi]._bucket;
435 ntarjan[w->_semi]._bucket = w;
436
437 w->_parent->LINK( w, &ntarjan[0] );
438
439 // Step 3:
440 for( NTarjan *vx = w->_parent->_bucket; vx; vx = vx->_bucket ) {
441 NTarjan *u = vx->EVAL();
442 vx->_dom = (u->_semi < vx->_semi) ? u : w->_parent;
443 }
444
445 // Cleanup any unreachable loops now. Unreachable loops are loops that
446 // flow into the main graph (and hence into ROOT) but are not reachable
447 // from above. Such code is dead, but requires a global pass to detect
448 // it; this global pass was the 'build_loop_tree' pass run just prior.
449 if( !_verify_only && whead->is_Region() ) {
450 for( uint i = 1; i < whead->req(); i++ ) {
451 if (!has_node(whead->in(i))) {
452 // Kill dead input path
453 assert( !visited.test(whead->in(i)->_idx),
454 "input with no loop must be dead" );
455 _igvn.delete_input_of(whead, i);
456 for (DUIterator_Fast jmax, j = whead->fast_outs(jmax); j < jmax; j++) {
457 Node* p = whead->fast_out(j);
458 if( p->is_Phi() ) {
459 _igvn.delete_input_of(p, i);
460 }
461 }
462 i--; // Rerun same iteration
463 } // End of if dead input path
464 } // End of for all input paths
465 } // End if if whead is a Region
466 } // End of for all Nodes in reverse DFS order
467
468 // Step 4:
469 for( i=2; i < dfsnum; i++ ) { // DFS order
470 NTarjan *w = &ntarjan[i];
471 assert(w->_control != NULL,"Bad DFS walk");
472 if( w->_dom != &ntarjan[w->_semi] )
473 w->_dom = w->_dom->_dom;
474 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later
475 }
476 // No immediate dominator for the root
477 NTarjan *w = &ntarjan[dfsorder[C->root()->_idx]];
478 w->_dom = NULL;
479 w->_parent = NULL;
480 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later
481
482 // Convert the dominator tree array into my kind of graph
483 for( i=1; i<dfsnum; i++ ) { // For all Tarjan vertices
484 NTarjan *t = &ntarjan[i]; // Handy access
485 assert(t->_control != NULL,"Bad DFS walk");
486 NTarjan *tdom = t->_dom; // Handy access to immediate dominator
487 if( tdom ) { // Root has no immediate dominator
488 _idom[t->_control->_idx] = tdom->_control; // Set immediate dominator
489 t->_dom_next = tdom->_dom_child; // Make me a sibling of parent's child
490 tdom->_dom_child = t; // Make me a child of my parent
491 } else
492 _idom[C->root()->_idx] = NULL; // Root
493 }
494 w->setdepth( C->unique()+1, _dom_depth ); // Set depth in dominator tree
495 // Pick up the 'top' node as well
496 _idom [C->top()->_idx] = C->root();
497 _dom_depth[C->top()->_idx] = 1;
498
499 // Debug Print of Dominator tree
500 if( PrintDominators ) {
501#ifndef PRODUCT
502 w->dump(0);
503#endif
504 }
505}
506
507// Perform DFS search. Setup 'vertex' as DFS to vertex mapping. Setup
508// 'semi' as vertex to DFS mapping. Set 'parent' to DFS parent.
509int NTarjan::DFS( NTarjan *ntarjan, VectorSet &visited, PhaseIdealLoop *pil, uint *dfsorder) {
510 // Allocate stack of size C->live_nodes()/8 to avoid frequent realloc
511 GrowableArray <Node *> dfstack(pil->C->live_nodes() >> 3);
512 Node *b = pil->C->root();
513 int dfsnum = 1;
514 dfsorder[b->_idx] = dfsnum; // Cache parent's dfsnum for a later use
515 dfstack.push(b);
516
517 while (dfstack.is_nonempty()) {
518 b = dfstack.pop();
519 if( !visited.test_set(b->_idx) ) { // Test node and flag it as visited
520 NTarjan *w = &ntarjan[dfsnum];
521 // Only fully process control nodes
522 w->_control = b; // Save actual node
523 // Use parent's cached dfsnum to identify "Parent in DFS"
524 w->_parent = &ntarjan[dfsorder[b->_idx]];
525 dfsorder[b->_idx] = dfsnum; // Save DFS order info
526 w->_semi = dfsnum; // Node to DFS map
527 w->_label = w; // DFS to vertex map
528 w->_ancestor = NULL; // Fast LINK & EVAL setup
529 w->_child = &ntarjan[0]; // Sentinal
530 w->_size = 1;
531 w->_bucket = NULL;
532
533 // Need DEF-USE info for this pass
534 for ( int i = b->outcnt(); i-- > 0; ) { // Put on stack backwards
535 Node* s = b->raw_out(i); // Get a use
536 // CFG nodes only and not dead stuff
537 if( s->is_CFG() && pil->has_node(s) && !visited.test(s->_idx) ) {
538 dfsorder[s->_idx] = dfsnum; // Cache parent's dfsnum for a later use
539 dfstack.push(s);
540 }
541 }
542 dfsnum++; // update after parent's dfsnum has been cached.
543 }
544 }
545
546 return dfsnum;
547}
548
549void NTarjan::COMPRESS()
550{
551 assert( _ancestor != 0, "" );
552 if( _ancestor->_ancestor != 0 ) {
553 _ancestor->COMPRESS( );
554 if( _ancestor->_label->_semi < _label->_semi )
555 _label = _ancestor->_label;
556 _ancestor = _ancestor->_ancestor;
557 }
558}
559
560NTarjan *NTarjan::EVAL() {
561 if( !_ancestor ) return _label;
562 COMPRESS();
563 return (_ancestor->_label->_semi >= _label->_semi) ? _label : _ancestor->_label;
564}
565
566void NTarjan::LINK( NTarjan *w, NTarjan *ntarjan0 ) {
567 NTarjan *s = w;
568 while( w->_label->_semi < s->_child->_label->_semi ) {
569 if( s->_size + s->_child->_child->_size >= (s->_child->_size << 1) ) {
570 s->_child->_ancestor = s;
571 s->_child = s->_child->_child;
572 } else {
573 s->_child->_size = s->_size;
574 s = s->_ancestor = s->_child;
575 }
576 }
577 s->_label = w->_label;
578 _size += w->_size;
579 if( _size < (w->_size << 1) ) {
580 NTarjan *tmp = s; s = _child; _child = tmp;
581 }
582 while( s != ntarjan0 ) {
583 s->_ancestor = this;
584 s = s->_child;
585 }
586}
587
588void NTarjan::setdepth( uint stack_size, uint *dom_depth ) {
589 NTarjan **top = NEW_RESOURCE_ARRAY(NTarjan*, stack_size);
590 NTarjan **next = top;
591 NTarjan **last;
592 uint depth = 0;
593 *top = this;
594 ++top;
595 do {
596 // next level
597 ++depth;
598 last = top;
599 do {
600 // Set current depth for all tarjans on this level
601 NTarjan *t = *next; // next tarjan from stack
602 ++next;
603 do {
604 dom_depth[t->_control->_idx] = depth; // Set depth in dominator tree
605 NTarjan *dom_child = t->_dom_child;
606 t = t->_dom_next; // next tarjan
607 if (dom_child != NULL) {
608 *top = dom_child; // save child on stack
609 ++top;
610 }
611 } while (t != NULL);
612 } while (next < last);
613 } while (last < top);
614}
615
616#ifndef PRODUCT
617void NTarjan::dump(int offset) const {
618 // Dump the data from this node
619 int i;
620 for(i = offset; i >0; i--) // Use indenting for tree structure
621 tty->print(" ");
622 tty->print("Dominator Node: ");
623 _control->dump(); // Control node for this dom node
624 tty->print("\n");
625 for(i = offset; i >0; i--) // Use indenting for tree structure
626 tty->print(" ");
627 tty->print("semi:%d, size:%d\n",_semi, _size);
628 for(i = offset; i >0; i--) // Use indenting for tree structure
629 tty->print(" ");
630 tty->print("DFS Parent: ");
631 if(_parent != NULL)
632 _parent->_control->dump(); // Parent in DFS
633 tty->print("\n");
634 for(i = offset; i >0; i--) // Use indenting for tree structure
635 tty->print(" ");
636 tty->print("Dom Parent: ");
637 if(_dom != NULL)
638 _dom->_control->dump(); // Parent in Dominator Tree
639 tty->print("\n");
640
641 // Recurse over remaining tree
642 if( _dom_child ) _dom_child->dump(offset+2); // Children in dominator tree
643 if( _dom_next ) _dom_next ->dump(offset ); // Siblings in dominator tree
644
645}
646#endif
647