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annotate src/share/vm/opto/domgraph.cpp @ 21738:28943e5044b5
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author | Tom Rodriguez <tom.rodriguez@oracle.com> |
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date | Thu, 04 Jun 2015 19:49:45 -0700 |
parents | 89152779163c |
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rev | line source |
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0 | 1 /* |
17524 | 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
1552
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "libadt/vectset.hpp" | |
27 #include "memory/allocation.hpp" | |
28 #include "opto/block.hpp" | |
29 #include "opto/machnode.hpp" | |
30 #include "opto/phaseX.hpp" | |
31 #include "opto/rootnode.hpp" | |
32 | |
0 | 33 // Portions of code courtesy of Clifford Click |
34 | |
35 // A data structure that holds all the information needed to find dominators. | |
36 struct Tarjan { | |
37 Block *_block; // Basic block for this info | |
38 | |
39 uint _semi; // Semi-dominators | |
40 uint _size; // Used for faster LINK and EVAL | |
41 Tarjan *_parent; // Parent in DFS | |
42 Tarjan *_label; // Used for LINK and EVAL | |
43 Tarjan *_ancestor; // Used for LINK and EVAL | |
44 Tarjan *_child; // Used for faster LINK and EVAL | |
45 Tarjan *_dom; // Parent in dominator tree (immediate dom) | |
46 Tarjan *_bucket; // Set of vertices with given semidominator | |
47 | |
48 Tarjan *_dom_child; // Child in dominator tree | |
49 Tarjan *_dom_next; // Next in dominator tree | |
50 | |
51 // Fast union-find work | |
52 void COMPRESS(); | |
53 Tarjan *EVAL(void); | |
54 void LINK( Tarjan *w, Tarjan *tarjan0 ); | |
55 | |
56 void setdepth( uint size ); | |
57 | |
58 }; | |
59 | |
60 // Compute the dominator tree of the CFG. The CFG must already have been | |
61 // constructed. This is the Lengauer & Tarjan O(E-alpha(E,V)) algorithm. | |
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62 void PhaseCFG::build_dominator_tree() { |
0 | 63 // Pre-grow the blocks array, prior to the ResourceMark kicking in |
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64 _blocks.map(number_of_blocks(), 0); |
0 | 65 |
66 ResourceMark rm; | |
67 // Setup mappings from my Graph to Tarjan's stuff and back | |
68 // Note: Tarjan uses 1-based arrays | |
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69 Tarjan* tarjan = NEW_RESOURCE_ARRAY(Tarjan, number_of_blocks() + 1); |
0 | 70 |
71 // Tarjan's algorithm, almost verbatim: | |
72 // Step 1: | |
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73 uint dfsnum = do_DFS(tarjan, number_of_blocks()); |
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74 if (dfsnum - 1 != number_of_blocks()) { // Check for unreachable loops! |
0 | 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 } | |
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91 _blocks._cnt = number_of_blocks(); |
0 | 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 | |
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97 for (uint i = number_of_blocks(); i >= 2; i--) { // For all vertices in DFS order |
0 | 98 Tarjan *w = &tarjan[i]; // Get vertex from DFS |
99 | |
100 // Step 2: | |
101 Node *whead = w->_block->head(); | |
12023 | 102 for (uint j = 1; j < whead->req(); j++) { |
103 Block* b = get_block_for_node(whead->in(j)); | |
0 | 104 Tarjan *vx = &tarjan[b->_pre_order]; |
105 Tarjan *u = vx->EVAL(); | |
106 if( u->_semi < w->_semi ) | |
107 w->_semi = u->_semi; | |
108 } | |
109 | |
110 // w is added to a bucket here, and only here. | |
111 // Thus w is in at most one bucket and the sum of all bucket sizes is O(n). | |
112 // Thus bucket can be a linked list. | |
113 // Thus we do not need a small integer name for each Block. | |
114 w->_bucket = tarjan[w->_semi]._bucket; | |
115 tarjan[w->_semi]._bucket = w; | |
116 | |
117 w->_parent->LINK( w, &tarjan[0] ); | |
118 | |
119 // Step 3: | |
120 for( Tarjan *vx = w->_parent->_bucket; vx; vx = vx->_bucket ) { | |
121 Tarjan *u = vx->EVAL(); | |
122 vx->_dom = (u->_semi < vx->_semi) ? u : w->_parent; | |
123 } | |
124 } | |
125 | |
126 // Step 4: | |
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127 for (uint i = 2; i <= number_of_blocks(); i++) { |
0 | 128 Tarjan *w = &tarjan[i]; |
129 if( w->_dom != &tarjan[w->_semi] ) | |
130 w->_dom = w->_dom->_dom; | |
131 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later | |
132 } | |
133 // No immediate dominator for the root | |
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134 Tarjan *w = &tarjan[get_root_block()->_pre_order]; |
0 | 135 w->_dom = NULL; |
136 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later | |
137 | |
138 // Convert the dominator tree array into my kind of graph | |
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139 for(uint i = 1; i <= number_of_blocks(); i++){ // For all Tarjan vertices |
0 | 140 Tarjan *t = &tarjan[i]; // Handy access |
141 Tarjan *tdom = t->_dom; // Handy access to immediate dominator | |
142 if( tdom ) { // Root has no immediate dominator | |
143 t->_block->_idom = tdom->_block; // Set immediate dominator | |
144 t->_dom_next = tdom->_dom_child; // Make me a sibling of parent's child | |
145 tdom->_dom_child = t; // Make me a child of my parent | |
146 } else | |
147 t->_block->_idom = NULL; // Root | |
148 } | |
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149 w->setdepth(number_of_blocks() + 1); // Set depth in dominator tree |
0 | 150 |
151 } | |
152 | |
153 class Block_Stack { | |
154 private: | |
155 struct Block_Descr { | |
156 Block *block; // Block | |
157 int index; // Index of block's successor pushed on stack | |
158 int freq_idx; // Index of block's most frequent successor | |
159 }; | |
160 Block_Descr *_stack_top; | |
161 Block_Descr *_stack_max; | |
162 Block_Descr *_stack; | |
163 Tarjan *_tarjan; | |
164 uint most_frequent_successor( Block *b ); | |
165 public: | |
166 Block_Stack(Tarjan *tarjan, int size) : _tarjan(tarjan) { | |
167 _stack = NEW_RESOURCE_ARRAY(Block_Descr, size); | |
168 _stack_max = _stack + size; | |
169 _stack_top = _stack - 1; // stack is empty | |
170 } | |
171 void push(uint pre_order, Block *b) { | |
172 Tarjan *t = &_tarjan[pre_order]; // Fast local access | |
173 b->_pre_order = pre_order; // Flag as visited | |
174 t->_block = b; // Save actual block | |
175 t->_semi = pre_order; // Block to DFS map | |
176 t->_label = t; // DFS to vertex map | |
177 t->_ancestor = NULL; // Fast LINK & EVAL setup | |
178 t->_child = &_tarjan[0]; // Sentenial | |
179 t->_size = 1; | |
180 t->_bucket = NULL; | |
181 if (pre_order == 1) | |
182 t->_parent = NULL; // first block doesn't have parent | |
183 else { | |
605 | 184 // Save parent (current top block on stack) in DFS |
0 | 185 t->_parent = &_tarjan[_stack_top->block->_pre_order]; |
186 } | |
187 // Now put this block on stack | |
188 ++_stack_top; | |
189 assert(_stack_top < _stack_max, ""); // assert if stack have to grow | |
190 _stack_top->block = b; | |
191 _stack_top->index = -1; | |
192 // Find the index into b->succs[] array of the most frequent successor. | |
193 _stack_top->freq_idx = most_frequent_successor(b); // freq_idx >= 0 | |
194 } | |
195 Block* pop() { Block* b = _stack_top->block; _stack_top--; return b; } | |
196 bool is_nonempty() { return (_stack_top >= _stack); } | |
197 bool last_successor() { return (_stack_top->index == _stack_top->freq_idx); } | |
198 Block* next_successor() { | |
199 int i = _stack_top->index; | |
200 i++; | |
201 if (i == _stack_top->freq_idx) i++; | |
202 if (i >= (int)(_stack_top->block->_num_succs)) { | |
203 i = _stack_top->freq_idx; // process most frequent successor last | |
204 } | |
205 _stack_top->index = i; | |
206 return _stack_top->block->_succs[ i ]; | |
207 } | |
208 }; | |
209 | |
210 // Find the index into the b->succs[] array of the most frequent successor. | |
211 uint Block_Stack::most_frequent_successor( Block *b ) { | |
212 uint freq_idx = 0; | |
213 int eidx = b->end_idx(); | |
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214 Node *n = b->get_node(eidx); |
0 | 215 int op = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : n->Opcode(); |
216 switch( op ) { | |
217 case Op_CountedLoopEnd: | |
218 case Op_If: { // Split frequency amongst children | |
219 float prob = n->as_MachIf()->_prob; | |
220 // Is succ[0] the TRUE branch or the FALSE branch? | |
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221 if( b->get_node(eidx+1)->Opcode() == Op_IfFalse ) |
0 | 222 prob = 1.0f - prob; |
223 freq_idx = prob < PROB_FAIR; // freq=1 for succ[0] < 0.5 prob | |
224 break; | |
225 } | |
226 case Op_Catch: // Split frequency amongst children | |
227 for( freq_idx = 0; freq_idx < b->_num_succs; freq_idx++ ) | |
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228 if( b->get_node(eidx+1+freq_idx)->as_CatchProj()->_con == CatchProjNode::fall_through_index ) |
0 | 229 break; |
230 // Handle case of no fall-thru (e.g., check-cast MUST throw an exception) | |
231 if( freq_idx == b->_num_succs ) freq_idx = 0; | |
232 break; | |
233 // Currently there is no support for finding out the most | |
234 // frequent successor for jumps, so lets just make it the first one | |
235 case Op_Jump: | |
236 case Op_Root: | |
237 case Op_Goto: | |
238 case Op_NeverBranch: | |
239 freq_idx = 0; // fall thru | |
240 break; | |
241 case Op_TailCall: | |
242 case Op_TailJump: | |
243 case Op_Return: | |
244 case Op_Halt: | |
245 case Op_Rethrow: | |
246 break; | |
247 default: | |
248 ShouldNotReachHere(); | |
249 } | |
250 return freq_idx; | |
251 } | |
252 | |
253 // Perform DFS search. Setup 'vertex' as DFS to vertex mapping. Setup | |
254 // 'semi' as vertex to DFS mapping. Set 'parent' to DFS parent. | |
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255 uint PhaseCFG::do_DFS(Tarjan *tarjan, uint rpo_counter) { |
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256 Block* root_block = get_root_block(); |
0 | 257 uint pre_order = 1; |
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258 // Allocate stack of size number_of_blocks() + 1 to avoid frequent realloc |
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259 Block_Stack bstack(tarjan, number_of_blocks() + 1); |
0 | 260 |
261 // Push on stack the state for the first block | |
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262 bstack.push(pre_order, root_block); |
0 | 263 ++pre_order; |
264 | |
265 while (bstack.is_nonempty()) { | |
266 if (!bstack.last_successor()) { | |
267 // Walk over all successors in pre-order (DFS). | |
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268 Block* next_block = bstack.next_successor(); |
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269 if (next_block->_pre_order == 0) { // Check for no-pre-order, not-visited |
0 | 270 // Push on stack the state of successor |
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271 bstack.push(pre_order, next_block); |
0 | 272 ++pre_order; |
273 } | |
274 } | |
275 else { | |
276 // Build a reverse post-order in the CFG _blocks array | |
277 Block *stack_top = bstack.pop(); | |
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278 stack_top->_rpo = --rpo_counter; |
0 | 279 _blocks.map(stack_top->_rpo, stack_top); |
280 } | |
281 } | |
282 return pre_order; | |
283 } | |
284 | |
285 void Tarjan::COMPRESS() | |
286 { | |
287 assert( _ancestor != 0, "" ); | |
288 if( _ancestor->_ancestor != 0 ) { | |
289 _ancestor->COMPRESS( ); | |
290 if( _ancestor->_label->_semi < _label->_semi ) | |
291 _label = _ancestor->_label; | |
292 _ancestor = _ancestor->_ancestor; | |
293 } | |
294 } | |
295 | |
296 Tarjan *Tarjan::EVAL() { | |
297 if( !_ancestor ) return _label; | |
298 COMPRESS(); | |
299 return (_ancestor->_label->_semi >= _label->_semi) ? _label : _ancestor->_label; | |
300 } | |
301 | |
302 void Tarjan::LINK( Tarjan *w, Tarjan *tarjan0 ) { | |
303 Tarjan *s = w; | |
304 while( w->_label->_semi < s->_child->_label->_semi ) { | |
305 if( s->_size + s->_child->_child->_size >= (s->_child->_size << 1) ) { | |
306 s->_child->_ancestor = s; | |
307 s->_child = s->_child->_child; | |
308 } else { | |
309 s->_child->_size = s->_size; | |
310 s = s->_ancestor = s->_child; | |
311 } | |
312 } | |
313 s->_label = w->_label; | |
314 _size += w->_size; | |
315 if( _size < (w->_size << 1) ) { | |
316 Tarjan *tmp = s; s = _child; _child = tmp; | |
317 } | |
318 while( s != tarjan0 ) { | |
319 s->_ancestor = this; | |
320 s = s->_child; | |
321 } | |
322 } | |
323 | |
324 void Tarjan::setdepth( uint stack_size ) { | |
325 Tarjan **top = NEW_RESOURCE_ARRAY(Tarjan*, stack_size); | |
326 Tarjan **next = top; | |
327 Tarjan **last; | |
328 uint depth = 0; | |
329 *top = this; | |
330 ++top; | |
331 do { | |
332 // next level | |
333 ++depth; | |
334 last = top; | |
335 do { | |
336 // Set current depth for all tarjans on this level | |
337 Tarjan *t = *next; // next tarjan from stack | |
338 ++next; | |
339 do { | |
340 t->_block->_dom_depth = depth; // Set depth in dominator tree | |
341 Tarjan *dom_child = t->_dom_child; | |
342 t = t->_dom_next; // next tarjan | |
343 if (dom_child != NULL) { | |
344 *top = dom_child; // save child on stack | |
345 ++top; | |
346 } | |
347 } while (t != NULL); | |
348 } while (next < last); | |
349 } while (last < top); | |
350 } | |
351 | |
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352 // Compute dominators on the Sea of Nodes form |
0 | 353 // A data structure that holds all the information needed to find dominators. |
354 struct NTarjan { | |
355 Node *_control; // Control node associated with this info | |
356 | |
357 uint _semi; // Semi-dominators | |
358 uint _size; // Used for faster LINK and EVAL | |
359 NTarjan *_parent; // Parent in DFS | |
360 NTarjan *_label; // Used for LINK and EVAL | |
361 NTarjan *_ancestor; // Used for LINK and EVAL | |
362 NTarjan *_child; // Used for faster LINK and EVAL | |
363 NTarjan *_dom; // Parent in dominator tree (immediate dom) | |
364 NTarjan *_bucket; // Set of vertices with given semidominator | |
365 | |
366 NTarjan *_dom_child; // Child in dominator tree | |
367 NTarjan *_dom_next; // Next in dominator tree | |
368 | |
369 // Perform DFS search. | |
370 // Setup 'vertex' as DFS to vertex mapping. | |
371 // Setup 'semi' as vertex to DFS mapping. | |
372 // Set 'parent' to DFS parent. | |
373 static int DFS( NTarjan *ntarjan, VectorSet &visited, PhaseIdealLoop *pil, uint *dfsorder ); | |
374 void setdepth( uint size, uint *dom_depth ); | |
375 | |
376 // Fast union-find work | |
377 void COMPRESS(); | |
378 NTarjan *EVAL(void); | |
379 void LINK( NTarjan *w, NTarjan *ntarjan0 ); | |
380 #ifndef PRODUCT | |
381 void dump(int offset) const; | |
382 #endif | |
383 }; | |
384 | |
385 // Compute the dominator tree of the sea of nodes. This version walks all CFG | |
386 // nodes (using the is_CFG() call) and places them in a dominator tree. Thus, | |
387 // it needs a count of the CFG nodes for the mapping table. This is the | |
388 // Lengauer & Tarjan O(E-alpha(E,V)) algorithm. | |
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389 void PhaseIdealLoop::Dominators() { |
0 | 390 ResourceMark rm; |
391 // Setup mappings from my Graph to Tarjan's stuff and back | |
392 // Note: Tarjan uses 1-based arrays | |
393 NTarjan *ntarjan = NEW_RESOURCE_ARRAY(NTarjan,C->unique()+1); | |
394 // Initialize _control field for fast reference | |
395 int i; | |
396 for( i= C->unique()-1; i>=0; i-- ) | |
397 ntarjan[i]._control = NULL; | |
398 | |
399 // Store the DFS order for the main loop | |
400 uint *dfsorder = NEW_RESOURCE_ARRAY(uint,C->unique()+1); | |
401 memset(dfsorder, max_uint, (C->unique()+1) * sizeof(uint)); | |
402 | |
403 // Tarjan's algorithm, almost verbatim: | |
404 // Step 1: | |
405 VectorSet visited(Thread::current()->resource_area()); | |
406 int dfsnum = NTarjan::DFS( ntarjan, visited, this, dfsorder); | |
407 | |
408 // Tarjan is using 1-based arrays, so these are some initialize flags | |
409 ntarjan[0]._size = ntarjan[0]._semi = 0; | |
410 ntarjan[0]._label = &ntarjan[0]; | |
411 | |
412 for( i = dfsnum-1; i>1; i-- ) { // For all nodes in reverse DFS order | |
413 NTarjan *w = &ntarjan[i]; // Get Node from DFS | |
414 assert(w->_control != NULL,"bad DFS walk"); | |
415 | |
416 // Step 2: | |
417 Node *whead = w->_control; | |
418 for( uint j=0; j < whead->req(); j++ ) { // For each predecessor | |
419 if( whead->in(j) == NULL || !whead->in(j)->is_CFG() ) | |
420 continue; // Only process control nodes | |
421 uint b = dfsorder[whead->in(j)->_idx]; | |
422 if(b == max_uint) continue; | |
423 NTarjan *vx = &ntarjan[b]; | |
424 NTarjan *u = vx->EVAL(); | |
425 if( u->_semi < w->_semi ) | |
426 w->_semi = u->_semi; | |
427 } | |
428 | |
429 // w is added to a bucket here, and only here. | |
430 // Thus w is in at most one bucket and the sum of all bucket sizes is O(n). | |
431 // Thus bucket can be a linked list. | |
432 w->_bucket = ntarjan[w->_semi]._bucket; | |
433 ntarjan[w->_semi]._bucket = w; | |
434 | |
435 w->_parent->LINK( w, &ntarjan[0] ); | |
436 | |
437 // Step 3: | |
438 for( NTarjan *vx = w->_parent->_bucket; vx; vx = vx->_bucket ) { | |
439 NTarjan *u = vx->EVAL(); | |
440 vx->_dom = (u->_semi < vx->_semi) ? u : w->_parent; | |
441 } | |
442 | |
443 // Cleanup any unreachable loops now. Unreachable loops are loops that | |
444 // flow into the main graph (and hence into ROOT) but are not reachable | |
445 // from above. Such code is dead, but requires a global pass to detect | |
446 // it; this global pass was the 'build_loop_tree' pass run just prior. | |
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447 if( !_verify_only && whead->is_Region() ) { |
0 | 448 for( uint i = 1; i < whead->req(); i++ ) { |
449 if (!has_node(whead->in(i))) { | |
450 // Kill dead input path | |
451 assert( !visited.test(whead->in(i)->_idx), | |
452 "input with no loop must be dead" ); | |
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453 _igvn.delete_input_of(whead, i); |
0 | 454 for (DUIterator_Fast jmax, j = whead->fast_outs(jmax); j < jmax; j++) { |
455 Node* p = whead->fast_out(j); | |
456 if( p->is_Phi() ) { | |
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457 _igvn.delete_input_of(p, i); |
0 | 458 } |
459 } | |
460 i--; // Rerun same iteration | |
461 } // End of if dead input path | |
462 } // End of for all input paths | |
463 } // End if if whead is a Region | |
464 } // End of for all Nodes in reverse DFS order | |
465 | |
466 // Step 4: | |
467 for( i=2; i < dfsnum; i++ ) { // DFS order | |
468 NTarjan *w = &ntarjan[i]; | |
469 assert(w->_control != NULL,"Bad DFS walk"); | |
470 if( w->_dom != &ntarjan[w->_semi] ) | |
471 w->_dom = w->_dom->_dom; | |
472 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later | |
473 } | |
474 // No immediate dominator for the root | |
475 NTarjan *w = &ntarjan[dfsorder[C->root()->_idx]]; | |
476 w->_dom = NULL; | |
477 w->_parent = NULL; | |
478 w->_dom_next = w->_dom_child = NULL; // Initialize for building tree later | |
479 | |
480 // Convert the dominator tree array into my kind of graph | |
481 for( i=1; i<dfsnum; i++ ) { // For all Tarjan vertices | |
482 NTarjan *t = &ntarjan[i]; // Handy access | |
483 assert(t->_control != NULL,"Bad DFS walk"); | |
484 NTarjan *tdom = t->_dom; // Handy access to immediate dominator | |
485 if( tdom ) { // Root has no immediate dominator | |
486 _idom[t->_control->_idx] = tdom->_control; // Set immediate dominator | |
487 t->_dom_next = tdom->_dom_child; // Make me a sibling of parent's child | |
488 tdom->_dom_child = t; // Make me a child of my parent | |
489 } else | |
490 _idom[C->root()->_idx] = NULL; // Root | |
491 } | |
492 w->setdepth( C->unique()+1, _dom_depth ); // Set depth in dominator tree | |
493 // Pick up the 'top' node as well | |
494 _idom [C->top()->_idx] = C->root(); | |
495 _dom_depth[C->top()->_idx] = 1; | |
496 | |
497 // Debug Print of Dominator tree | |
498 if( PrintDominators ) { | |
499 #ifndef PRODUCT | |
500 w->dump(0); | |
501 #endif | |
502 } | |
503 } | |
504 | |
505 // Perform DFS search. Setup 'vertex' as DFS to vertex mapping. Setup | |
506 // 'semi' as vertex to DFS mapping. Set 'parent' to DFS parent. | |
507 int NTarjan::DFS( NTarjan *ntarjan, VectorSet &visited, PhaseIdealLoop *pil, uint *dfsorder) { | |
508 // Allocate stack of size C->unique()/8 to avoid frequent realloc | |
509 GrowableArray <Node *> dfstack(pil->C->unique() >> 3); | |
510 Node *b = pil->C->root(); | |
511 int dfsnum = 1; | |
512 dfsorder[b->_idx] = dfsnum; // Cache parent's dfsnum for a later use | |
513 dfstack.push(b); | |
514 | |
515 while (dfstack.is_nonempty()) { | |
516 b = dfstack.pop(); | |
517 if( !visited.test_set(b->_idx) ) { // Test node and flag it as visited | |
518 NTarjan *w = &ntarjan[dfsnum]; | |
519 // Only fully process control nodes | |
520 w->_control = b; // Save actual node | |
521 // Use parent's cached dfsnum to identify "Parent in DFS" | |
522 w->_parent = &ntarjan[dfsorder[b->_idx]]; | |
523 dfsorder[b->_idx] = dfsnum; // Save DFS order info | |
524 w->_semi = dfsnum; // Node to DFS map | |
525 w->_label = w; // DFS to vertex map | |
526 w->_ancestor = NULL; // Fast LINK & EVAL setup | |
527 w->_child = &ntarjan[0]; // Sentinal | |
528 w->_size = 1; | |
529 w->_bucket = NULL; | |
530 | |
531 // Need DEF-USE info for this pass | |
532 for ( int i = b->outcnt(); i-- > 0; ) { // Put on stack backwards | |
533 Node* s = b->raw_out(i); // Get a use | |
534 // CFG nodes only and not dead stuff | |
535 if( s->is_CFG() && pil->has_node(s) && !visited.test(s->_idx) ) { | |
536 dfsorder[s->_idx] = dfsnum; // Cache parent's dfsnum for a later use | |
537 dfstack.push(s); | |
538 } | |
539 } | |
540 dfsnum++; // update after parent's dfsnum has been cached. | |
541 } | |
542 } | |
543 | |
544 return dfsnum; | |
545 } | |
546 | |
547 void NTarjan::COMPRESS() | |
548 { | |
549 assert( _ancestor != 0, "" ); | |
550 if( _ancestor->_ancestor != 0 ) { | |
551 _ancestor->COMPRESS( ); | |
552 if( _ancestor->_label->_semi < _label->_semi ) | |
553 _label = _ancestor->_label; | |
554 _ancestor = _ancestor->_ancestor; | |
555 } | |
556 } | |
557 | |
558 NTarjan *NTarjan::EVAL() { | |
559 if( !_ancestor ) return _label; | |
560 COMPRESS(); | |
561 return (_ancestor->_label->_semi >= _label->_semi) ? _label : _ancestor->_label; | |
562 } | |
563 | |
564 void NTarjan::LINK( NTarjan *w, NTarjan *ntarjan0 ) { | |
565 NTarjan *s = w; | |
566 while( w->_label->_semi < s->_child->_label->_semi ) { | |
567 if( s->_size + s->_child->_child->_size >= (s->_child->_size << 1) ) { | |
568 s->_child->_ancestor = s; | |
569 s->_child = s->_child->_child; | |
570 } else { | |
571 s->_child->_size = s->_size; | |
572 s = s->_ancestor = s->_child; | |
573 } | |
574 } | |
575 s->_label = w->_label; | |
576 _size += w->_size; | |
577 if( _size < (w->_size << 1) ) { | |
578 NTarjan *tmp = s; s = _child; _child = tmp; | |
579 } | |
580 while( s != ntarjan0 ) { | |
581 s->_ancestor = this; | |
582 s = s->_child; | |
583 } | |
584 } | |
585 | |
586 void NTarjan::setdepth( uint stack_size, uint *dom_depth ) { | |
587 NTarjan **top = NEW_RESOURCE_ARRAY(NTarjan*, stack_size); | |
588 NTarjan **next = top; | |
589 NTarjan **last; | |
590 uint depth = 0; | |
591 *top = this; | |
592 ++top; | |
593 do { | |
594 // next level | |
595 ++depth; | |
596 last = top; | |
597 do { | |
598 // Set current depth for all tarjans on this level | |
599 NTarjan *t = *next; // next tarjan from stack | |
600 ++next; | |
601 do { | |
602 dom_depth[t->_control->_idx] = depth; // Set depth in dominator tree | |
603 NTarjan *dom_child = t->_dom_child; | |
604 t = t->_dom_next; // next tarjan | |
605 if (dom_child != NULL) { | |
606 *top = dom_child; // save child on stack | |
607 ++top; | |
608 } | |
609 } while (t != NULL); | |
610 } while (next < last); | |
611 } while (last < top); | |
612 } | |
613 | |
614 #ifndef PRODUCT | |
615 void NTarjan::dump(int offset) const { | |
616 // Dump the data from this node | |
617 int i; | |
618 for(i = offset; i >0; i--) // Use indenting for tree structure | |
619 tty->print(" "); | |
620 tty->print("Dominator Node: "); | |
621 _control->dump(); // Control node for this dom node | |
622 tty->print("\n"); | |
623 for(i = offset; i >0; i--) // Use indenting for tree structure | |
624 tty->print(" "); | |
625 tty->print("semi:%d, size:%d\n",_semi, _size); | |
626 for(i = offset; i >0; i--) // Use indenting for tree structure | |
627 tty->print(" "); | |
628 tty->print("DFS Parent: "); | |
629 if(_parent != NULL) | |
630 _parent->_control->dump(); // Parent in DFS | |
631 tty->print("\n"); | |
632 for(i = offset; i >0; i--) // Use indenting for tree structure | |
633 tty->print(" "); | |
634 tty->print("Dom Parent: "); | |
635 if(_dom != NULL) | |
636 _dom->_control->dump(); // Parent in Dominator Tree | |
637 tty->print("\n"); | |
638 | |
639 // Recurse over remaining tree | |
640 if( _dom_child ) _dom_child->dump(offset+2); // Children in dominator tree | |
641 if( _dom_next ) _dom_next ->dump(offset ); // Siblings in dominator tree | |
642 | |
643 } | |
644 #endif |