Mercurial > hg > truffle
annotate src/share/vm/opto/coalesce.cpp @ 6027:8a2e5a6a19a4
7143490: G1: Remove HeapRegion::_top_at_conc_mark_count
Summary: Removed the HeapRegion::_top_at_conc_mark_count field. It is no longer needed as a result of the changes for 6888336 and 7127706. Refactored the closures that finalize and verify the liveness counting data so that common functionality was placed into a base class.
Reviewed-by: brutisso, tonyp
author | johnc |
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date | Wed, 25 Apr 2012 10:23:12 -0700 |
parents | c7b60b601eb4 |
children | 8373c19be854 |
rev | line source |
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0 | 1 /* |
1972 | 2 * Copyright (c) 1997, 2010, 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 "memory/allocation.inline.hpp" | |
27 #include "opto/block.hpp" | |
28 #include "opto/cfgnode.hpp" | |
29 #include "opto/chaitin.hpp" | |
30 #include "opto/coalesce.hpp" | |
31 #include "opto/connode.hpp" | |
32 #include "opto/indexSet.hpp" | |
33 #include "opto/machnode.hpp" | |
34 #include "opto/matcher.hpp" | |
35 #include "opto/regmask.hpp" | |
0 | 36 |
37 //============================================================================= | |
38 //------------------------------reset_uf_map----------------------------------- | |
39 void PhaseChaitin::reset_uf_map( uint maxlrg ) { | |
40 _maxlrg = maxlrg; | |
41 // Force the Union-Find mapping to be at least this large | |
42 _uf_map.extend(_maxlrg,0); | |
43 // Initialize it to be the ID mapping. | |
44 for( uint i=0; i<_maxlrg; i++ ) | |
45 _uf_map.map(i,i); | |
46 } | |
47 | |
48 //------------------------------compress_uf_map-------------------------------- | |
49 // Make all Nodes map directly to their final live range; no need for | |
50 // the Union-Find mapping after this call. | |
51 void PhaseChaitin::compress_uf_map_for_nodes( ) { | |
52 // For all Nodes, compress mapping | |
53 uint unique = _names.Size(); | |
54 for( uint i=0; i<unique; i++ ) { | |
55 uint lrg = _names[i]; | |
56 uint compressed_lrg = Find(lrg); | |
57 if( lrg != compressed_lrg ) | |
58 _names.map(i,compressed_lrg); | |
59 } | |
60 } | |
61 | |
62 //------------------------------Find------------------------------------------- | |
63 // Straight out of Tarjan's union-find algorithm | |
64 uint PhaseChaitin::Find_compress( uint lrg ) { | |
65 uint cur = lrg; | |
66 uint next = _uf_map[cur]; | |
67 while( next != cur ) { // Scan chain of equivalences | |
68 assert( next < cur, "always union smaller" ); | |
69 cur = next; // until find a fixed-point | |
70 next = _uf_map[cur]; | |
71 } | |
72 // Core of union-find algorithm: update chain of | |
73 // equivalences to be equal to the root. | |
74 while( lrg != next ) { | |
75 uint tmp = _uf_map[lrg]; | |
76 _uf_map.map(lrg, next); | |
77 lrg = tmp; | |
78 } | |
79 return lrg; | |
80 } | |
81 | |
82 //------------------------------Find------------------------------------------- | |
83 // Straight out of Tarjan's union-find algorithm | |
84 uint PhaseChaitin::Find_compress( const Node *n ) { | |
85 uint lrg = Find_compress(_names[n->_idx]); | |
86 _names.map(n->_idx,lrg); | |
87 return lrg; | |
88 } | |
89 | |
90 //------------------------------Find_const------------------------------------- | |
91 // Like Find above, but no path compress, so bad asymptotic behavior | |
92 uint PhaseChaitin::Find_const( uint lrg ) const { | |
93 if( !lrg ) return lrg; // Ignore the zero LRG | |
94 // Off the end? This happens during debugging dumps when you got | |
95 // brand new live ranges but have not told the allocator yet. | |
96 if( lrg >= _maxlrg ) return lrg; | |
97 uint next = _uf_map[lrg]; | |
98 while( next != lrg ) { // Scan chain of equivalences | |
99 assert( next < lrg, "always union smaller" ); | |
100 lrg = next; // until find a fixed-point | |
101 next = _uf_map[lrg]; | |
102 } | |
103 return next; | |
104 } | |
105 | |
106 //------------------------------Find------------------------------------------- | |
107 // Like Find above, but no path compress, so bad asymptotic behavior | |
108 uint PhaseChaitin::Find_const( const Node *n ) const { | |
109 if( n->_idx >= _names.Size() ) return 0; // not mapped, usual for debug dump | |
110 return Find_const( _names[n->_idx] ); | |
111 } | |
112 | |
113 //------------------------------Union------------------------------------------ | |
114 // union 2 sets together. | |
115 void PhaseChaitin::Union( const Node *src_n, const Node *dst_n ) { | |
116 uint src = Find(src_n); | |
117 uint dst = Find(dst_n); | |
118 assert( src, "" ); | |
119 assert( dst, "" ); | |
120 assert( src < _maxlrg, "oob" ); | |
121 assert( dst < _maxlrg, "oob" ); | |
122 assert( src < dst, "always union smaller" ); | |
123 _uf_map.map(dst,src); | |
124 } | |
125 | |
126 //------------------------------new_lrg---------------------------------------- | |
127 void PhaseChaitin::new_lrg( const Node *x, uint lrg ) { | |
128 // Make the Node->LRG mapping | |
129 _names.extend(x->_idx,lrg); | |
130 // Make the Union-Find mapping an identity function | |
131 _uf_map.extend(lrg,lrg); | |
132 } | |
133 | |
134 //------------------------------clone_projs------------------------------------ | |
605 | 135 // After cloning some rematerialized instruction, clone any MachProj's that |
0 | 136 // follow it. Example: Intel zero is XOR, kills flags. Sparc FP constants |
137 // use G3 as an address temp. | |
138 int PhaseChaitin::clone_projs( Block *b, uint idx, Node *con, Node *copy, uint &maxlrg ) { | |
139 Block *bcon = _cfg._bbs[con->_idx]; | |
140 uint cindex = bcon->find_node(con); | |
141 Node *con_next = bcon->_nodes[cindex+1]; | |
3842 | 142 if( con_next->in(0) != con || !con_next->is_MachProj() ) |
0 | 143 return false; // No MachProj's follow |
144 | |
145 // Copy kills after the cloned constant | |
146 Node *kills = con_next->clone(); | |
147 kills->set_req( 0, copy ); | |
148 b->_nodes.insert( idx, kills ); | |
149 _cfg._bbs.map( kills->_idx, b ); | |
150 new_lrg( kills, maxlrg++ ); | |
151 return true; | |
152 } | |
153 | |
154 //------------------------------compact---------------------------------------- | |
155 // Renumber the live ranges to compact them. Makes the IFG smaller. | |
156 void PhaseChaitin::compact() { | |
157 // Current the _uf_map contains a series of short chains which are headed | |
158 // by a self-cycle. All the chains run from big numbers to little numbers. | |
159 // The Find() call chases the chains & shortens them for the next Find call. | |
160 // We are going to change this structure slightly. Numbers above a moving | |
161 // wave 'i' are unchanged. Numbers below 'j' point directly to their | |
162 // compacted live range with no further chaining. There are no chains or | |
163 // cycles below 'i', so the Find call no longer works. | |
164 uint j=1; | |
165 uint i; | |
166 for( i=1; i < _maxlrg; i++ ) { | |
167 uint lr = _uf_map[i]; | |
168 // Ignore unallocated live ranges | |
169 if( !lr ) continue; | |
170 assert( lr <= i, "" ); | |
171 _uf_map.map(i, ( lr == i ) ? j++ : _uf_map[lr]); | |
172 } | |
173 if( false ) // PrintOptoCompactLiveRanges | |
174 printf("Compacted %d LRs from %d\n",i-j,i); | |
175 // Now change the Node->LR mapping to reflect the compacted names | |
176 uint unique = _names.Size(); | |
177 for( i=0; i<unique; i++ ) | |
178 _names.map(i,_uf_map[_names[i]]); | |
179 | |
180 // Reset the Union-Find mapping | |
181 reset_uf_map(j); | |
182 | |
183 } | |
184 | |
185 //============================================================================= | |
186 //------------------------------Dump------------------------------------------- | |
187 #ifndef PRODUCT | |
188 void PhaseCoalesce::dump( Node *n ) const { | |
189 // Being a const function means I cannot use 'Find' | |
190 uint r = _phc.Find(n); | |
191 tty->print("L%d/N%d ",r,n->_idx); | |
192 } | |
193 | |
194 //------------------------------dump------------------------------------------- | |
195 void PhaseCoalesce::dump() const { | |
196 // I know I have a block layout now, so I can print blocks in a loop | |
197 for( uint i=0; i<_phc._cfg._num_blocks; i++ ) { | |
198 uint j; | |
199 Block *b = _phc._cfg._blocks[i]; | |
200 // Print a nice block header | |
201 tty->print("B%d: ",b->_pre_order); | |
202 for( j=1; j<b->num_preds(); j++ ) | |
203 tty->print("B%d ", _phc._cfg._bbs[b->pred(j)->_idx]->_pre_order); | |
204 tty->print("-> "); | |
205 for( j=0; j<b->_num_succs; j++ ) | |
206 tty->print("B%d ",b->_succs[j]->_pre_order); | |
207 tty->print(" IDom: B%d/#%d\n", b->_idom ? b->_idom->_pre_order : 0, b->_dom_depth); | |
208 uint cnt = b->_nodes.size(); | |
209 for( j=0; j<cnt; j++ ) { | |
210 Node *n = b->_nodes[j]; | |
211 dump( n ); | |
212 tty->print("\t%s\t",n->Name()); | |
213 | |
214 // Dump the inputs | |
215 uint k; // Exit value of loop | |
216 for( k=0; k<n->req(); k++ ) // For all required inputs | |
217 if( n->in(k) ) dump( n->in(k) ); | |
218 else tty->print("_ "); | |
219 int any_prec = 0; | |
220 for( ; k<n->len(); k++ ) // For all precedence inputs | |
221 if( n->in(k) ) { | |
222 if( !any_prec++ ) tty->print(" |"); | |
223 dump( n->in(k) ); | |
224 } | |
225 | |
226 // Dump node-specific info | |
227 n->dump_spec(tty); | |
228 tty->print("\n"); | |
229 | |
230 } | |
231 tty->print("\n"); | |
232 } | |
233 } | |
234 #endif | |
235 | |
236 //------------------------------combine_these_two------------------------------ | |
237 // Combine the live ranges def'd by these 2 Nodes. N2 is an input to N1. | |
238 void PhaseCoalesce::combine_these_two( Node *n1, Node *n2 ) { | |
239 uint lr1 = _phc.Find(n1); | |
240 uint lr2 = _phc.Find(n2); | |
241 if( lr1 != lr2 && // Different live ranges already AND | |
242 !_phc._ifg->test_edge_sq( lr1, lr2 ) ) { // Do not interfere | |
243 LRG *lrg1 = &_phc.lrgs(lr1); | |
244 LRG *lrg2 = &_phc.lrgs(lr2); | |
245 // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK. | |
246 | |
247 // Now, why is int->oop OK? We end up declaring a raw-pointer as an oop | |
248 // and in general that's a bad thing. However, int->oop conversions only | |
249 // happen at GC points, so the lifetime of the misclassified raw-pointer | |
250 // is from the CheckCastPP (that converts it to an oop) backwards up | |
251 // through a merge point and into the slow-path call, and around the | |
252 // diamond up to the heap-top check and back down into the slow-path call. | |
253 // The misclassified raw pointer is NOT live across the slow-path call, | |
254 // and so does not appear in any GC info, so the fact that it is | |
255 // misclassified is OK. | |
256 | |
257 if( (lrg1->_is_oop || !lrg2->_is_oop) && // not an oop->int cast AND | |
258 // Compatible final mask | |
259 lrg1->mask().overlap( lrg2->mask() ) ) { | |
260 // Merge larger into smaller. | |
261 if( lr1 > lr2 ) { | |
262 uint tmp = lr1; lr1 = lr2; lr2 = tmp; | |
263 Node *n = n1; n1 = n2; n2 = n; | |
264 LRG *ltmp = lrg1; lrg1 = lrg2; lrg2 = ltmp; | |
265 } | |
266 // Union lr2 into lr1 | |
267 _phc.Union( n1, n2 ); | |
268 if (lrg1->_maxfreq < lrg2->_maxfreq) | |
269 lrg1->_maxfreq = lrg2->_maxfreq; | |
270 // Merge in the IFG | |
271 _phc._ifg->Union( lr1, lr2 ); | |
272 // Combine register restrictions | |
273 lrg1->AND(lrg2->mask()); | |
274 } | |
275 } | |
276 } | |
277 | |
278 //------------------------------coalesce_driver-------------------------------- | |
279 // Copy coalescing | |
280 void PhaseCoalesce::coalesce_driver( ) { | |
281 | |
282 verify(); | |
283 // Coalesce from high frequency to low | |
284 for( uint i=0; i<_phc._cfg._num_blocks; i++ ) | |
285 coalesce( _phc._blks[i] ); | |
286 | |
287 } | |
288 | |
289 //------------------------------insert_copy_with_overlap----------------------- | |
290 // I am inserting copies to come out of SSA form. In the general case, I am | |
291 // doing a parallel renaming. I'm in the Named world now, so I can't do a | |
292 // general parallel renaming. All the copies now use "names" (live-ranges) | |
293 // to carry values instead of the explicit use-def chains. Suppose I need to | |
294 // insert 2 copies into the same block. They copy L161->L128 and L128->L132. | |
295 // If I insert them in the wrong order then L128 will get clobbered before it | |
296 // can get used by the second copy. This cannot happen in the SSA model; | |
297 // direct use-def chains get me the right value. It DOES happen in the named | |
298 // model so I have to handle the reordering of copies. | |
299 // | |
300 // In general, I need to topo-sort the placed copies to avoid conflicts. | |
301 // Its possible to have a closed cycle of copies (e.g., recirculating the same | |
302 // values around a loop). In this case I need a temp to break the cycle. | |
303 void PhaseAggressiveCoalesce::insert_copy_with_overlap( Block *b, Node *copy, uint dst_name, uint src_name ) { | |
304 | |
305 // Scan backwards for the locations of the last use of the dst_name. | |
306 // I am about to clobber the dst_name, so the copy must be inserted | |
307 // after the last use. Last use is really first-use on a backwards scan. | |
308 uint i = b->end_idx()-1; | |
309 while( 1 ) { | |
310 Node *n = b->_nodes[i]; | |
311 // Check for end of virtual copies; this is also the end of the | |
312 // parallel renaming effort. | |
313 if( n->_idx < _unique ) break; | |
314 uint idx = n->is_Copy(); | |
3842 | 315 assert( idx || n->is_Con() || n->is_MachProj(), "Only copies during parallel renaming" ); |
0 | 316 if( idx && _phc.Find(n->in(idx)) == dst_name ) break; |
317 i--; | |
318 } | |
319 uint last_use_idx = i; | |
320 | |
321 // Also search for any kill of src_name that exits the block. | |
322 // Since the copy uses src_name, I have to come before any kill. | |
323 uint kill_src_idx = b->end_idx(); | |
324 // There can be only 1 kill that exits any block and that is | |
325 // the last kill. Thus it is the first kill on a backwards scan. | |
326 i = b->end_idx()-1; | |
327 while( 1 ) { | |
328 Node *n = b->_nodes[i]; | |
329 // Check for end of virtual copies; this is also the end of the | |
330 // parallel renaming effort. | |
331 if( n->_idx < _unique ) break; | |
3842 | 332 assert( n->is_Copy() || n->is_Con() || n->is_MachProj(), "Only copies during parallel renaming" ); |
0 | 333 if( _phc.Find(n) == src_name ) { |
334 kill_src_idx = i; | |
335 break; | |
336 } | |
337 i--; | |
338 } | |
339 // Need a temp? Last use of dst comes after the kill of src? | |
340 if( last_use_idx >= kill_src_idx ) { | |
341 // Need to break a cycle with a temp | |
342 uint idx = copy->is_Copy(); | |
343 Node *tmp = copy->clone(); | |
344 _phc.new_lrg(tmp,_phc._maxlrg++); | |
345 // Insert new temp between copy and source | |
346 tmp ->set_req(idx,copy->in(idx)); | |
347 copy->set_req(idx,tmp); | |
348 // Save source in temp early, before source is killed | |
349 b->_nodes.insert(kill_src_idx,tmp); | |
350 _phc._cfg._bbs.map( tmp->_idx, b ); | |
351 last_use_idx++; | |
352 } | |
353 | |
354 // Insert just after last use | |
355 b->_nodes.insert(last_use_idx+1,copy); | |
356 } | |
357 | |
358 //------------------------------insert_copies---------------------------------- | |
359 void PhaseAggressiveCoalesce::insert_copies( Matcher &matcher ) { | |
360 // We do LRGs compressing and fix a liveout data only here since the other | |
361 // place in Split() is guarded by the assert which we never hit. | |
362 _phc.compress_uf_map_for_nodes(); | |
363 // Fix block's liveout data for compressed live ranges. | |
364 for(uint lrg = 1; lrg < _phc._maxlrg; lrg++ ) { | |
365 uint compressed_lrg = _phc.Find(lrg); | |
366 if( lrg != compressed_lrg ) { | |
367 for( uint bidx = 0; bidx < _phc._cfg._num_blocks; bidx++ ) { | |
368 IndexSet *liveout = _phc._live->live(_phc._cfg._blocks[bidx]); | |
369 if( liveout->member(lrg) ) { | |
370 liveout->remove(lrg); | |
371 liveout->insert(compressed_lrg); | |
372 } | |
373 } | |
374 } | |
375 } | |
376 | |
377 // All new nodes added are actual copies to replace virtual copies. | |
378 // Nodes with index less than '_unique' are original, non-virtual Nodes. | |
379 _unique = C->unique(); | |
380 | |
381 for( uint i=0; i<_phc._cfg._num_blocks; i++ ) { | |
382 Block *b = _phc._cfg._blocks[i]; | |
383 uint cnt = b->num_preds(); // Number of inputs to the Phi | |
384 | |
385 for( uint l = 1; l<b->_nodes.size(); l++ ) { | |
386 Node *n = b->_nodes[l]; | |
387 | |
388 // Do not use removed-copies, use copied value instead | |
389 uint ncnt = n->req(); | |
390 for( uint k = 1; k<ncnt; k++ ) { | |
391 Node *copy = n->in(k); | |
392 uint cidx = copy->is_Copy(); | |
393 if( cidx ) { | |
394 Node *def = copy->in(cidx); | |
395 if( _phc.Find(copy) == _phc.Find(def) ) | |
396 n->set_req(k,def); | |
397 } | |
398 } | |
399 | |
400 // Remove any explicit copies that get coalesced. | |
401 uint cidx = n->is_Copy(); | |
402 if( cidx ) { | |
403 Node *def = n->in(cidx); | |
404 if( _phc.Find(n) == _phc.Find(def) ) { | |
405 n->replace_by(def); | |
406 n->set_req(cidx,NULL); | |
407 b->_nodes.remove(l); | |
408 l--; | |
409 continue; | |
410 } | |
411 } | |
412 | |
413 if( n->is_Phi() ) { | |
414 // Get the chosen name for the Phi | |
415 uint phi_name = _phc.Find( n ); | |
416 // Ignore the pre-allocated specials | |
417 if( !phi_name ) continue; | |
418 // Check for mismatch inputs to Phi | |
419 for( uint j = 1; j<cnt; j++ ) { | |
420 Node *m = n->in(j); | |
421 uint src_name = _phc.Find(m); | |
422 if( src_name != phi_name ) { | |
423 Block *pred = _phc._cfg._bbs[b->pred(j)->_idx]; | |
424 Node *copy; | |
425 assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach"); | |
426 // Rematerialize constants instead of copying them | |
427 if( m->is_Mach() && m->as_Mach()->is_Con() && | |
428 m->as_Mach()->rematerialize() ) { | |
429 copy = m->clone(); | |
430 // Insert the copy in the predecessor basic block | |
431 pred->add_inst(copy); | |
432 // Copy any flags as well | |
433 _phc.clone_projs( pred, pred->end_idx(), m, copy, _phc._maxlrg ); | |
434 } else { | |
435 const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()]; | |
436 copy = new (C) MachSpillCopyNode(m,*rm,*rm); | |
437 // Find a good place to insert. Kinda tricky, use a subroutine | |
438 insert_copy_with_overlap(pred,copy,phi_name,src_name); | |
439 } | |
440 // Insert the copy in the use-def chain | |
441 n->set_req( j, copy ); | |
442 _phc._cfg._bbs.map( copy->_idx, pred ); | |
443 // Extend ("register allocate") the names array for the copy. | |
444 _phc._names.extend( copy->_idx, phi_name ); | |
445 } // End of if Phi names do not match | |
446 } // End of for all inputs to Phi | |
447 } else { // End of if Phi | |
448 | |
449 // Now check for 2-address instructions | |
450 uint idx; | |
451 if( n->is_Mach() && (idx=n->as_Mach()->two_adr()) ) { | |
452 // Get the chosen name for the Node | |
453 uint name = _phc.Find( n ); | |
454 assert( name, "no 2-address specials" ); | |
455 // Check for name mis-match on the 2-address input | |
456 Node *m = n->in(idx); | |
457 if( _phc.Find(m) != name ) { | |
458 Node *copy; | |
459 assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach"); | |
460 // At this point it is unsafe to extend live ranges (6550579). | |
461 // Rematerialize only constants as we do for Phi above. | |
462 if( m->is_Mach() && m->as_Mach()->is_Con() && | |
463 m->as_Mach()->rematerialize() ) { | |
464 copy = m->clone(); | |
465 // Insert the copy in the basic block, just before us | |
466 b->_nodes.insert( l++, copy ); | |
467 if( _phc.clone_projs( b, l, m, copy, _phc._maxlrg ) ) | |
468 l++; | |
469 } else { | |
470 const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()]; | |
471 copy = new (C) MachSpillCopyNode( m, *rm, *rm ); | |
472 // Insert the copy in the basic block, just before us | |
473 b->_nodes.insert( l++, copy ); | |
474 } | |
475 // Insert the copy in the use-def chain | |
476 n->set_req(idx, copy ); | |
477 // Extend ("register allocate") the names array for the copy. | |
478 _phc._names.extend( copy->_idx, name ); | |
479 _phc._cfg._bbs.map( copy->_idx, b ); | |
480 } | |
481 | |
482 } // End of is two-adr | |
483 | |
484 // Insert a copy at a debug use for a lrg which has high frequency | |
673 | 485 if( b->_freq < OPTO_DEBUG_SPLIT_FREQ || b->is_uncommon(_phc._cfg._bbs) ) { |
0 | 486 // Walk the debug inputs to the node and check for lrg freq |
487 JVMState* jvms = n->jvms(); | |
488 uint debug_start = jvms ? jvms->debug_start() : 999999; | |
489 uint debug_end = jvms ? jvms->debug_end() : 999999; | |
490 for(uint inpidx = debug_start; inpidx < debug_end; inpidx++) { | |
491 // Do not split monitors; they are only needed for debug table | |
492 // entries and need no code. | |
493 if( jvms->is_monitor_use(inpidx) ) continue; | |
494 Node *inp = n->in(inpidx); | |
495 uint nidx = _phc.n2lidx(inp); | |
496 LRG &lrg = lrgs(nidx); | |
497 | |
498 // If this lrg has a high frequency use/def | |
673 | 499 if( lrg._maxfreq >= _phc.high_frequency_lrg() ) { |
0 | 500 // If the live range is also live out of this block (like it |
501 // would be for a fast/slow idiom), the normal spill mechanism | |
502 // does an excellent job. If it is not live out of this block | |
503 // (like it would be for debug info to uncommon trap) splitting | |
504 // the live range now allows a better allocation in the high | |
505 // frequency blocks. | |
506 // Build_IFG_virtual has converted the live sets to | |
507 // live-IN info, not live-OUT info. | |
508 uint k; | |
509 for( k=0; k < b->_num_succs; k++ ) | |
510 if( _phc._live->live(b->_succs[k])->member( nidx ) ) | |
511 break; // Live in to some successor block? | |
512 if( k < b->_num_succs ) | |
513 continue; // Live out; do not pre-split | |
514 // Split the lrg at this use | |
515 const RegMask *rm = C->matcher()->idealreg2spillmask[inp->ideal_reg()]; | |
516 Node *copy = new (C) MachSpillCopyNode( inp, *rm, *rm ); | |
517 // Insert the copy in the use-def chain | |
518 n->set_req(inpidx, copy ); | |
519 // Insert the copy in the basic block, just before us | |
520 b->_nodes.insert( l++, copy ); | |
521 // Extend ("register allocate") the names array for the copy. | |
522 _phc.new_lrg( copy, _phc._maxlrg++ ); | |
523 _phc._cfg._bbs.map( copy->_idx, b ); | |
524 //tty->print_cr("Split a debug use in Aggressive Coalesce"); | |
525 } // End of if high frequency use/def | |
526 } // End of for all debug inputs | |
527 } // End of if low frequency safepoint | |
528 | |
529 } // End of if Phi | |
530 | |
531 } // End of for all instructions | |
532 } // End of for all blocks | |
533 } | |
534 | |
535 //============================================================================= | |
536 //------------------------------coalesce--------------------------------------- | |
537 // Aggressive (but pessimistic) copy coalescing of a single block | |
538 | |
539 // The following coalesce pass represents a single round of aggressive | |
540 // pessimistic coalesce. "Aggressive" means no attempt to preserve | |
541 // colorability when coalescing. This occasionally means more spills, but | |
542 // it also means fewer rounds of coalescing for better code - and that means | |
543 // faster compiles. | |
544 | |
545 // "Pessimistic" means we do not hit the fixed point in one pass (and we are | |
546 // reaching for the least fixed point to boot). This is typically solved | |
547 // with a few more rounds of coalescing, but the compiler must run fast. We | |
548 // could optimistically coalescing everything touching PhiNodes together | |
549 // into one big live range, then check for self-interference. Everywhere | |
550 // the live range interferes with self it would have to be split. Finding | |
551 // the right split points can be done with some heuristics (based on | |
552 // expected frequency of edges in the live range). In short, it's a real | |
553 // research problem and the timeline is too short to allow such research. | |
554 // Further thoughts: (1) build the LR in a pass, (2) find self-interference | |
555 // in another pass, (3) per each self-conflict, split, (4) split by finding | |
556 // the low-cost cut (min-cut) of the LR, (5) edges in the LR are weighted | |
557 // according to the GCM algorithm (or just exec freq on CFG edges). | |
558 | |
559 void PhaseAggressiveCoalesce::coalesce( Block *b ) { | |
560 // Copies are still "virtual" - meaning we have not made them explicitly | |
561 // copies. Instead, Phi functions of successor blocks have mis-matched | |
562 // live-ranges. If I fail to coalesce, I'll have to insert a copy to line | |
563 // up the live-ranges. Check for Phis in successor blocks. | |
564 uint i; | |
565 for( i=0; i<b->_num_succs; i++ ) { | |
566 Block *bs = b->_succs[i]; | |
567 // Find index of 'b' in 'bs' predecessors | |
568 uint j=1; | |
569 while( _phc._cfg._bbs[bs->pred(j)->_idx] != b ) j++; | |
570 // Visit all the Phis in successor block | |
571 for( uint k = 1; k<bs->_nodes.size(); k++ ) { | |
572 Node *n = bs->_nodes[k]; | |
573 if( !n->is_Phi() ) break; | |
574 combine_these_two( n, n->in(j) ); | |
575 } | |
576 } // End of for all successor blocks | |
577 | |
578 | |
579 // Check _this_ block for 2-address instructions and copies. | |
580 uint cnt = b->end_idx(); | |
581 for( i = 1; i<cnt; i++ ) { | |
582 Node *n = b->_nodes[i]; | |
583 uint idx; | |
584 // 2-address instructions have a virtual Copy matching their input | |
585 // to their output | |
586 if( n->is_Mach() && (idx = n->as_Mach()->two_adr()) ) { | |
587 MachNode *mach = n->as_Mach(); | |
588 combine_these_two( mach, mach->in(idx) ); | |
589 } | |
590 } // End of for all instructions in block | |
591 } | |
592 | |
593 //============================================================================= | |
594 //------------------------------PhaseConservativeCoalesce---------------------- | |
595 PhaseConservativeCoalesce::PhaseConservativeCoalesce( PhaseChaitin &chaitin ) : PhaseCoalesce(chaitin) { | |
596 _ulr.initialize(_phc._maxlrg); | |
597 } | |
598 | |
599 //------------------------------verify----------------------------------------- | |
600 void PhaseConservativeCoalesce::verify() { | |
601 #ifdef ASSERT | |
602 _phc.set_was_low(); | |
603 #endif | |
604 } | |
605 | |
606 //------------------------------union_helper----------------------------------- | |
607 void PhaseConservativeCoalesce::union_helper( Node *lr1_node, Node *lr2_node, uint lr1, uint lr2, Node *src_def, Node *dst_copy, Node *src_copy, Block *b, uint bindex ) { | |
608 // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the | |
609 // union-find tree | |
610 _phc.Union( lr1_node, lr2_node ); | |
611 | |
612 // Single-def live range ONLY if both live ranges are single-def. | |
613 // If both are single def, then src_def powers one live range | |
614 // and def_copy powers the other. After merging, src_def powers | |
615 // the combined live range. | |
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616 lrgs(lr1)._def = (lrgs(lr1).is_multidef() || |
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617 lrgs(lr2).is_multidef() ) |
0 | 618 ? NodeSentinel : src_def; |
619 lrgs(lr2)._def = NULL; // No def for lrg 2 | |
620 lrgs(lr2).Clear(); // Force empty mask for LRG 2 | |
621 //lrgs(lr2)._size = 0; // Live-range 2 goes dead | |
622 lrgs(lr1)._is_oop |= lrgs(lr2)._is_oop; | |
623 lrgs(lr2)._is_oop = 0; // In particular, not an oop for GC info | |
624 | |
625 if (lrgs(lr1)._maxfreq < lrgs(lr2)._maxfreq) | |
626 lrgs(lr1)._maxfreq = lrgs(lr2)._maxfreq; | |
627 | |
628 // Copy original value instead. Intermediate copies go dead, and | |
629 // the dst_copy becomes useless. | |
630 int didx = dst_copy->is_Copy(); | |
631 dst_copy->set_req( didx, src_def ); | |
632 // Add copy to free list | |
633 // _phc.free_spillcopy(b->_nodes[bindex]); | |
634 assert( b->_nodes[bindex] == dst_copy, "" ); | |
635 dst_copy->replace_by( dst_copy->in(didx) ); | |
636 dst_copy->set_req( didx, NULL); | |
637 b->_nodes.remove(bindex); | |
638 if( bindex < b->_ihrp_index ) b->_ihrp_index--; | |
639 if( bindex < b->_fhrp_index ) b->_fhrp_index--; | |
640 | |
641 // Stretched lr1; add it to liveness of intermediate blocks | |
642 Block *b2 = _phc._cfg._bbs[src_copy->_idx]; | |
643 while( b != b2 ) { | |
644 b = _phc._cfg._bbs[b->pred(1)->_idx]; | |
645 _phc._live->live(b)->insert(lr1); | |
646 } | |
647 } | |
648 | |
649 //------------------------------compute_separating_interferences--------------- | |
650 // Factored code from copy_copy that computes extra interferences from | |
651 // lengthening a live range by double-coalescing. | |
652 uint PhaseConservativeCoalesce::compute_separating_interferences(Node *dst_copy, Node *src_copy, Block *b, uint bindex, RegMask &rm, uint reg_degree, uint rm_size, uint lr1, uint lr2 ) { | |
653 | |
654 assert(!lrgs(lr1)._fat_proj, "cannot coalesce fat_proj"); | |
655 assert(!lrgs(lr2)._fat_proj, "cannot coalesce fat_proj"); | |
656 Node *prev_copy = dst_copy->in(dst_copy->is_Copy()); | |
657 Block *b2 = b; | |
658 uint bindex2 = bindex; | |
659 while( 1 ) { | |
660 // Find previous instruction | |
661 bindex2--; // Chain backwards 1 instruction | |
662 while( bindex2 == 0 ) { // At block start, find prior block | |
663 assert( b2->num_preds() == 2, "cannot double coalesce across c-flow" ); | |
664 b2 = _phc._cfg._bbs[b2->pred(1)->_idx]; | |
665 bindex2 = b2->end_idx()-1; | |
666 } | |
667 // Get prior instruction | |
668 assert(bindex2 < b2->_nodes.size(), "index out of bounds"); | |
669 Node *x = b2->_nodes[bindex2]; | |
670 if( x == prev_copy ) { // Previous copy in copy chain? | |
671 if( prev_copy == src_copy)// Found end of chain and all interferences | |
672 break; // So break out of loop | |
673 // Else work back one in copy chain | |
674 prev_copy = prev_copy->in(prev_copy->is_Copy()); | |
675 } else { // Else collect interferences | |
676 uint lidx = _phc.Find(x); | |
677 // Found another def of live-range being stretched? | |
678 if( lidx == lr1 ) return max_juint; | |
679 if( lidx == lr2 ) return max_juint; | |
680 | |
681 // If we attempt to coalesce across a bound def | |
682 if( lrgs(lidx).is_bound() ) { | |
683 // Do not let the coalesced LRG expect to get the bound color | |
684 rm.SUBTRACT( lrgs(lidx).mask() ); | |
685 // Recompute rm_size | |
686 rm_size = rm.Size(); | |
687 //if( rm._flags ) rm_size += 1000000; | |
688 if( reg_degree >= rm_size ) return max_juint; | |
689 } | |
690 if( rm.overlap(lrgs(lidx).mask()) ) { | |
691 // Insert lidx into union LRG; returns TRUE if actually inserted | |
692 if( _ulr.insert(lidx) ) { | |
693 // Infinite-stack neighbors do not alter colorability, as they | |
694 // can always color to some other color. | |
695 if( !lrgs(lidx).mask().is_AllStack() ) { | |
696 // If this coalesce will make any new neighbor uncolorable, | |
697 // do not coalesce. | |
698 if( lrgs(lidx).just_lo_degree() ) | |
699 return max_juint; | |
700 // Bump our degree | |
701 if( ++reg_degree >= rm_size ) | |
702 return max_juint; | |
703 } // End of if not infinite-stack neighbor | |
704 } // End of if actually inserted | |
705 } // End of if live range overlaps | |
605 | 706 } // End of else collect interferences for 1 node |
707 } // End of while forever, scan back for interferences | |
0 | 708 return reg_degree; |
709 } | |
710 | |
711 //------------------------------update_ifg------------------------------------- | |
712 void PhaseConservativeCoalesce::update_ifg(uint lr1, uint lr2, IndexSet *n_lr1, IndexSet *n_lr2) { | |
713 // Some original neighbors of lr1 might have gone away | |
714 // because the constrained register mask prevented them. | |
715 // Remove lr1 from such neighbors. | |
716 IndexSetIterator one(n_lr1); | |
717 uint neighbor; | |
718 LRG &lrg1 = lrgs(lr1); | |
719 while ((neighbor = one.next()) != 0) | |
720 if( !_ulr.member(neighbor) ) | |
721 if( _phc._ifg->neighbors(neighbor)->remove(lr1) ) | |
722 lrgs(neighbor).inc_degree( -lrg1.compute_degree(lrgs(neighbor)) ); | |
723 | |
724 | |
725 // lr2 is now called (coalesced into) lr1. | |
726 // Remove lr2 from the IFG. | |
727 IndexSetIterator two(n_lr2); | |
728 LRG &lrg2 = lrgs(lr2); | |
729 while ((neighbor = two.next()) != 0) | |
730 if( _phc._ifg->neighbors(neighbor)->remove(lr2) ) | |
731 lrgs(neighbor).inc_degree( -lrg2.compute_degree(lrgs(neighbor)) ); | |
732 | |
733 // Some neighbors of intermediate copies now interfere with the | |
734 // combined live range. | |
735 IndexSetIterator three(&_ulr); | |
736 while ((neighbor = three.next()) != 0) | |
737 if( _phc._ifg->neighbors(neighbor)->insert(lr1) ) | |
738 lrgs(neighbor).inc_degree( lrg1.compute_degree(lrgs(neighbor)) ); | |
739 } | |
740 | |
741 //------------------------------record_bias------------------------------------ | |
742 static void record_bias( const PhaseIFG *ifg, int lr1, int lr2 ) { | |
743 // Tag copy bias here | |
744 if( !ifg->lrgs(lr1)._copy_bias ) | |
745 ifg->lrgs(lr1)._copy_bias = lr2; | |
746 if( !ifg->lrgs(lr2)._copy_bias ) | |
747 ifg->lrgs(lr2)._copy_bias = lr1; | |
748 } | |
749 | |
750 //------------------------------copy_copy-------------------------------------- | |
751 // See if I can coalesce a series of multiple copies together. I need the | |
752 // final dest copy and the original src copy. They can be the same Node. | |
753 // Compute the compatible register masks. | |
754 bool PhaseConservativeCoalesce::copy_copy( Node *dst_copy, Node *src_copy, Block *b, uint bindex ) { | |
755 | |
756 if( !dst_copy->is_SpillCopy() ) return false; | |
757 if( !src_copy->is_SpillCopy() ) return false; | |
758 Node *src_def = src_copy->in(src_copy->is_Copy()); | |
759 uint lr1 = _phc.Find(dst_copy); | |
760 uint lr2 = _phc.Find(src_def ); | |
761 | |
762 // Same live ranges already? | |
763 if( lr1 == lr2 ) return false; | |
764 | |
765 // Interfere? | |
766 if( _phc._ifg->test_edge_sq( lr1, lr2 ) ) return false; | |
767 | |
768 // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK. | |
769 if( !lrgs(lr1)._is_oop && lrgs(lr2)._is_oop ) // not an oop->int cast | |
770 return false; | |
771 | |
772 // Coalescing between an aligned live range and a mis-aligned live range? | |
773 // No, no! Alignment changes how we count degree. | |
774 if( lrgs(lr1)._fat_proj != lrgs(lr2)._fat_proj ) | |
775 return false; | |
776 | |
777 // Sort; use smaller live-range number | |
778 Node *lr1_node = dst_copy; | |
779 Node *lr2_node = src_def; | |
780 if( lr1 > lr2 ) { | |
781 uint tmp = lr1; lr1 = lr2; lr2 = tmp; | |
782 lr1_node = src_def; lr2_node = dst_copy; | |
783 } | |
784 | |
785 // Check for compatibility of the 2 live ranges by | |
786 // intersecting their allowed register sets. | |
787 RegMask rm = lrgs(lr1).mask(); | |
788 rm.AND(lrgs(lr2).mask()); | |
789 // Number of bits free | |
790 uint rm_size = rm.Size(); | |
791 | |
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792 if (UseFPUForSpilling && rm.is_AllStack() ) { |
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793 // Don't coalesce when frequency difference is large |
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794 Block *dst_b = _phc._cfg._bbs[dst_copy->_idx]; |
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795 Block *src_def_b = _phc._cfg._bbs[src_def->_idx]; |
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796 if (src_def_b->_freq > 10*dst_b->_freq ) |
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797 return false; |
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798 } |
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799 |
0 | 800 // If we can use any stack slot, then effective size is infinite |
801 if( rm.is_AllStack() ) rm_size += 1000000; | |
802 // Incompatible masks, no way to coalesce | |
803 if( rm_size == 0 ) return false; | |
804 | |
805 // Another early bail-out test is when we are double-coalescing and the | |
605 | 806 // 2 copies are separated by some control flow. |
0 | 807 if( dst_copy != src_copy ) { |
808 Block *src_b = _phc._cfg._bbs[src_copy->_idx]; | |
809 Block *b2 = b; | |
810 while( b2 != src_b ) { | |
811 if( b2->num_preds() > 2 ){// Found merge-point | |
812 _phc._lost_opp_cflow_coalesce++; | |
813 // extra record_bias commented out because Chris believes it is not | |
814 // productive. Since we can record only 1 bias, we want to choose one | |
815 // that stands a chance of working and this one probably does not. | |
816 //record_bias( _phc._lrgs, lr1, lr2 ); | |
817 return false; // To hard to find all interferences | |
818 } | |
819 b2 = _phc._cfg._bbs[b2->pred(1)->_idx]; | |
820 } | |
821 } | |
822 | |
823 // Union the two interference sets together into '_ulr' | |
824 uint reg_degree = _ulr.lrg_union( lr1, lr2, rm_size, _phc._ifg, rm ); | |
825 | |
826 if( reg_degree >= rm_size ) { | |
827 record_bias( _phc._ifg, lr1, lr2 ); | |
828 return false; | |
829 } | |
830 | |
831 // Now I need to compute all the interferences between dst_copy and | |
832 // src_copy. I'm not willing visit the entire interference graph, so | |
833 // I limit my search to things in dst_copy's block or in a straight | |
834 // line of previous blocks. I give up at merge points or when I get | |
835 // more interferences than my degree. I can stop when I find src_copy. | |
836 if( dst_copy != src_copy ) { | |
837 reg_degree = compute_separating_interferences(dst_copy, src_copy, b, bindex, rm, rm_size, reg_degree, lr1, lr2 ); | |
838 if( reg_degree == max_juint ) { | |
839 record_bias( _phc._ifg, lr1, lr2 ); | |
840 return false; | |
841 } | |
842 } // End of if dst_copy & src_copy are different | |
843 | |
844 | |
845 // ---- THE COMBINED LRG IS COLORABLE ---- | |
846 | |
847 // YEAH - Now coalesce this copy away | |
848 assert( lrgs(lr1).num_regs() == lrgs(lr2).num_regs(), "" ); | |
849 | |
850 IndexSet *n_lr1 = _phc._ifg->neighbors(lr1); | |
851 IndexSet *n_lr2 = _phc._ifg->neighbors(lr2); | |
852 | |
853 // Update the interference graph | |
854 update_ifg(lr1, lr2, n_lr1, n_lr2); | |
855 | |
856 _ulr.remove(lr1); | |
857 | |
858 // Uncomment the following code to trace Coalescing in great detail. | |
859 // | |
860 //if (false) { | |
861 // tty->cr(); | |
862 // tty->print_cr("#######################################"); | |
863 // tty->print_cr("union %d and %d", lr1, lr2); | |
864 // n_lr1->dump(); | |
865 // n_lr2->dump(); | |
866 // tty->print_cr("resulting set is"); | |
867 // _ulr.dump(); | |
868 //} | |
869 | |
870 // Replace n_lr1 with the new combined live range. _ulr will use | |
871 // n_lr1's old memory on the next iteration. n_lr2 is cleared to | |
872 // send its internal memory to the free list. | |
873 _ulr.swap(n_lr1); | |
874 _ulr.clear(); | |
875 n_lr2->clear(); | |
876 | |
877 lrgs(lr1).set_degree( _phc._ifg->effective_degree(lr1) ); | |
878 lrgs(lr2).set_degree( 0 ); | |
879 | |
880 // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the | |
881 // union-find tree | |
882 union_helper( lr1_node, lr2_node, lr1, lr2, src_def, dst_copy, src_copy, b, bindex ); | |
883 // Combine register restrictions | |
884 lrgs(lr1).set_mask(rm); | |
885 lrgs(lr1).compute_set_mask_size(); | |
886 lrgs(lr1)._cost += lrgs(lr2)._cost; | |
887 lrgs(lr1)._area += lrgs(lr2)._area; | |
888 | |
889 // While its uncommon to successfully coalesce live ranges that started out | |
890 // being not-lo-degree, it can happen. In any case the combined coalesced | |
891 // live range better Simplify nicely. | |
892 lrgs(lr1)._was_lo = 1; | |
893 | |
894 // kinda expensive to do all the time | |
895 //tty->print_cr("warning: slow verify happening"); | |
896 //_phc._ifg->verify( &_phc ); | |
897 return true; | |
898 } | |
899 | |
900 //------------------------------coalesce--------------------------------------- | |
901 // Conservative (but pessimistic) copy coalescing of a single block | |
902 void PhaseConservativeCoalesce::coalesce( Block *b ) { | |
903 // Bail out on infrequent blocks | |
904 if( b->is_uncommon(_phc._cfg._bbs) ) | |
905 return; | |
906 // Check this block for copies. | |
907 for( uint i = 1; i<b->end_idx(); i++ ) { | |
908 // Check for actual copies on inputs. Coalesce a copy into its | |
909 // input if use and copy's input are compatible. | |
910 Node *copy1 = b->_nodes[i]; | |
911 uint idx1 = copy1->is_Copy(); | |
912 if( !idx1 ) continue; // Not a copy | |
913 | |
914 if( copy_copy(copy1,copy1,b,i) ) { | |
915 i--; // Retry, same location in block | |
916 PhaseChaitin::_conserv_coalesce++; // Collect stats on success | |
917 continue; | |
918 } | |
919 | |
920 /* do not attempt pairs. About 1/2 of all pairs can be removed by | |
921 post-alloc. The other set are too few to bother. | |
922 Node *copy2 = copy1->in(idx1); | |
923 uint idx2 = copy2->is_Copy(); | |
924 if( !idx2 ) continue; | |
925 if( copy_copy(copy1,copy2,b,i) ) { | |
926 i--; // Retry, same location in block | |
927 PhaseChaitin::_conserv_coalesce_pair++; // Collect stats on success | |
928 continue; | |
929 } | |
930 */ | |
931 } | |
932 } |