Mercurial > hg > graal-compiler
annotate src/share/vm/opto/coalesce.cpp @ 1722:effb55808a18
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author | johnc |
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date | Wed, 18 Aug 2010 17:44:33 -0400 |
parents | c18cbe5936b8 |
children | f55c4f82ab9d |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2009, 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 | |
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7 * published by the Free Software Foundation. | |
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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 * | |
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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 | |
25 #include "incls/_precompiled.incl" | |
26 #include "incls/_coalesce.cpp.incl" | |
27 | |
28 //============================================================================= | |
29 //------------------------------reset_uf_map----------------------------------- | |
30 void PhaseChaitin::reset_uf_map( uint maxlrg ) { | |
31 _maxlrg = maxlrg; | |
32 // Force the Union-Find mapping to be at least this large | |
33 _uf_map.extend(_maxlrg,0); | |
34 // Initialize it to be the ID mapping. | |
35 for( uint i=0; i<_maxlrg; i++ ) | |
36 _uf_map.map(i,i); | |
37 } | |
38 | |
39 //------------------------------compress_uf_map-------------------------------- | |
40 // Make all Nodes map directly to their final live range; no need for | |
41 // the Union-Find mapping after this call. | |
42 void PhaseChaitin::compress_uf_map_for_nodes( ) { | |
43 // For all Nodes, compress mapping | |
44 uint unique = _names.Size(); | |
45 for( uint i=0; i<unique; i++ ) { | |
46 uint lrg = _names[i]; | |
47 uint compressed_lrg = Find(lrg); | |
48 if( lrg != compressed_lrg ) | |
49 _names.map(i,compressed_lrg); | |
50 } | |
51 } | |
52 | |
53 //------------------------------Find------------------------------------------- | |
54 // Straight out of Tarjan's union-find algorithm | |
55 uint PhaseChaitin::Find_compress( uint lrg ) { | |
56 uint cur = lrg; | |
57 uint next = _uf_map[cur]; | |
58 while( next != cur ) { // Scan chain of equivalences | |
59 assert( next < cur, "always union smaller" ); | |
60 cur = next; // until find a fixed-point | |
61 next = _uf_map[cur]; | |
62 } | |
63 // Core of union-find algorithm: update chain of | |
64 // equivalences to be equal to the root. | |
65 while( lrg != next ) { | |
66 uint tmp = _uf_map[lrg]; | |
67 _uf_map.map(lrg, next); | |
68 lrg = tmp; | |
69 } | |
70 return lrg; | |
71 } | |
72 | |
73 //------------------------------Find------------------------------------------- | |
74 // Straight out of Tarjan's union-find algorithm | |
75 uint PhaseChaitin::Find_compress( const Node *n ) { | |
76 uint lrg = Find_compress(_names[n->_idx]); | |
77 _names.map(n->_idx,lrg); | |
78 return lrg; | |
79 } | |
80 | |
81 //------------------------------Find_const------------------------------------- | |
82 // Like Find above, but no path compress, so bad asymptotic behavior | |
83 uint PhaseChaitin::Find_const( uint lrg ) const { | |
84 if( !lrg ) return lrg; // Ignore the zero LRG | |
85 // Off the end? This happens during debugging dumps when you got | |
86 // brand new live ranges but have not told the allocator yet. | |
87 if( lrg >= _maxlrg ) return lrg; | |
88 uint next = _uf_map[lrg]; | |
89 while( next != lrg ) { // Scan chain of equivalences | |
90 assert( next < lrg, "always union smaller" ); | |
91 lrg = next; // until find a fixed-point | |
92 next = _uf_map[lrg]; | |
93 } | |
94 return next; | |
95 } | |
96 | |
97 //------------------------------Find------------------------------------------- | |
98 // Like Find above, but no path compress, so bad asymptotic behavior | |
99 uint PhaseChaitin::Find_const( const Node *n ) const { | |
100 if( n->_idx >= _names.Size() ) return 0; // not mapped, usual for debug dump | |
101 return Find_const( _names[n->_idx] ); | |
102 } | |
103 | |
104 //------------------------------Union------------------------------------------ | |
105 // union 2 sets together. | |
106 void PhaseChaitin::Union( const Node *src_n, const Node *dst_n ) { | |
107 uint src = Find(src_n); | |
108 uint dst = Find(dst_n); | |
109 assert( src, "" ); | |
110 assert( dst, "" ); | |
111 assert( src < _maxlrg, "oob" ); | |
112 assert( dst < _maxlrg, "oob" ); | |
113 assert( src < dst, "always union smaller" ); | |
114 _uf_map.map(dst,src); | |
115 } | |
116 | |
117 //------------------------------new_lrg---------------------------------------- | |
118 void PhaseChaitin::new_lrg( const Node *x, uint lrg ) { | |
119 // Make the Node->LRG mapping | |
120 _names.extend(x->_idx,lrg); | |
121 // Make the Union-Find mapping an identity function | |
122 _uf_map.extend(lrg,lrg); | |
123 } | |
124 | |
125 //------------------------------clone_projs------------------------------------ | |
605 | 126 // After cloning some rematerialized instruction, clone any MachProj's that |
0 | 127 // follow it. Example: Intel zero is XOR, kills flags. Sparc FP constants |
128 // use G3 as an address temp. | |
129 int PhaseChaitin::clone_projs( Block *b, uint idx, Node *con, Node *copy, uint &maxlrg ) { | |
130 Block *bcon = _cfg._bbs[con->_idx]; | |
131 uint cindex = bcon->find_node(con); | |
132 Node *con_next = bcon->_nodes[cindex+1]; | |
133 if( con_next->in(0) != con || con_next->Opcode() != Op_MachProj ) | |
134 return false; // No MachProj's follow | |
135 | |
136 // Copy kills after the cloned constant | |
137 Node *kills = con_next->clone(); | |
138 kills->set_req( 0, copy ); | |
139 b->_nodes.insert( idx, kills ); | |
140 _cfg._bbs.map( kills->_idx, b ); | |
141 new_lrg( kills, maxlrg++ ); | |
142 return true; | |
143 } | |
144 | |
145 //------------------------------compact---------------------------------------- | |
146 // Renumber the live ranges to compact them. Makes the IFG smaller. | |
147 void PhaseChaitin::compact() { | |
148 // Current the _uf_map contains a series of short chains which are headed | |
149 // by a self-cycle. All the chains run from big numbers to little numbers. | |
150 // The Find() call chases the chains & shortens them for the next Find call. | |
151 // We are going to change this structure slightly. Numbers above a moving | |
152 // wave 'i' are unchanged. Numbers below 'j' point directly to their | |
153 // compacted live range with no further chaining. There are no chains or | |
154 // cycles below 'i', so the Find call no longer works. | |
155 uint j=1; | |
156 uint i; | |
157 for( i=1; i < _maxlrg; i++ ) { | |
158 uint lr = _uf_map[i]; | |
159 // Ignore unallocated live ranges | |
160 if( !lr ) continue; | |
161 assert( lr <= i, "" ); | |
162 _uf_map.map(i, ( lr == i ) ? j++ : _uf_map[lr]); | |
163 } | |
164 if( false ) // PrintOptoCompactLiveRanges | |
165 printf("Compacted %d LRs from %d\n",i-j,i); | |
166 // Now change the Node->LR mapping to reflect the compacted names | |
167 uint unique = _names.Size(); | |
168 for( i=0; i<unique; i++ ) | |
169 _names.map(i,_uf_map[_names[i]]); | |
170 | |
171 // Reset the Union-Find mapping | |
172 reset_uf_map(j); | |
173 | |
174 } | |
175 | |
176 //============================================================================= | |
177 //------------------------------Dump------------------------------------------- | |
178 #ifndef PRODUCT | |
179 void PhaseCoalesce::dump( Node *n ) const { | |
180 // Being a const function means I cannot use 'Find' | |
181 uint r = _phc.Find(n); | |
182 tty->print("L%d/N%d ",r,n->_idx); | |
183 } | |
184 | |
185 //------------------------------dump------------------------------------------- | |
186 void PhaseCoalesce::dump() const { | |
187 // I know I have a block layout now, so I can print blocks in a loop | |
188 for( uint i=0; i<_phc._cfg._num_blocks; i++ ) { | |
189 uint j; | |
190 Block *b = _phc._cfg._blocks[i]; | |
191 // Print a nice block header | |
192 tty->print("B%d: ",b->_pre_order); | |
193 for( j=1; j<b->num_preds(); j++ ) | |
194 tty->print("B%d ", _phc._cfg._bbs[b->pred(j)->_idx]->_pre_order); | |
195 tty->print("-> "); | |
196 for( j=0; j<b->_num_succs; j++ ) | |
197 tty->print("B%d ",b->_succs[j]->_pre_order); | |
198 tty->print(" IDom: B%d/#%d\n", b->_idom ? b->_idom->_pre_order : 0, b->_dom_depth); | |
199 uint cnt = b->_nodes.size(); | |
200 for( j=0; j<cnt; j++ ) { | |
201 Node *n = b->_nodes[j]; | |
202 dump( n ); | |
203 tty->print("\t%s\t",n->Name()); | |
204 | |
205 // Dump the inputs | |
206 uint k; // Exit value of loop | |
207 for( k=0; k<n->req(); k++ ) // For all required inputs | |
208 if( n->in(k) ) dump( n->in(k) ); | |
209 else tty->print("_ "); | |
210 int any_prec = 0; | |
211 for( ; k<n->len(); k++ ) // For all precedence inputs | |
212 if( n->in(k) ) { | |
213 if( !any_prec++ ) tty->print(" |"); | |
214 dump( n->in(k) ); | |
215 } | |
216 | |
217 // Dump node-specific info | |
218 n->dump_spec(tty); | |
219 tty->print("\n"); | |
220 | |
221 } | |
222 tty->print("\n"); | |
223 } | |
224 } | |
225 #endif | |
226 | |
227 //------------------------------combine_these_two------------------------------ | |
228 // Combine the live ranges def'd by these 2 Nodes. N2 is an input to N1. | |
229 void PhaseCoalesce::combine_these_two( Node *n1, Node *n2 ) { | |
230 uint lr1 = _phc.Find(n1); | |
231 uint lr2 = _phc.Find(n2); | |
232 if( lr1 != lr2 && // Different live ranges already AND | |
233 !_phc._ifg->test_edge_sq( lr1, lr2 ) ) { // Do not interfere | |
234 LRG *lrg1 = &_phc.lrgs(lr1); | |
235 LRG *lrg2 = &_phc.lrgs(lr2); | |
236 // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK. | |
237 | |
238 // Now, why is int->oop OK? We end up declaring a raw-pointer as an oop | |
239 // and in general that's a bad thing. However, int->oop conversions only | |
240 // happen at GC points, so the lifetime of the misclassified raw-pointer | |
241 // is from the CheckCastPP (that converts it to an oop) backwards up | |
242 // through a merge point and into the slow-path call, and around the | |
243 // diamond up to the heap-top check and back down into the slow-path call. | |
244 // The misclassified raw pointer is NOT live across the slow-path call, | |
245 // and so does not appear in any GC info, so the fact that it is | |
246 // misclassified is OK. | |
247 | |
248 if( (lrg1->_is_oop || !lrg2->_is_oop) && // not an oop->int cast AND | |
249 // Compatible final mask | |
250 lrg1->mask().overlap( lrg2->mask() ) ) { | |
251 // Merge larger into smaller. | |
252 if( lr1 > lr2 ) { | |
253 uint tmp = lr1; lr1 = lr2; lr2 = tmp; | |
254 Node *n = n1; n1 = n2; n2 = n; | |
255 LRG *ltmp = lrg1; lrg1 = lrg2; lrg2 = ltmp; | |
256 } | |
257 // Union lr2 into lr1 | |
258 _phc.Union( n1, n2 ); | |
259 if (lrg1->_maxfreq < lrg2->_maxfreq) | |
260 lrg1->_maxfreq = lrg2->_maxfreq; | |
261 // Merge in the IFG | |
262 _phc._ifg->Union( lr1, lr2 ); | |
263 // Combine register restrictions | |
264 lrg1->AND(lrg2->mask()); | |
265 } | |
266 } | |
267 } | |
268 | |
269 //------------------------------coalesce_driver-------------------------------- | |
270 // Copy coalescing | |
271 void PhaseCoalesce::coalesce_driver( ) { | |
272 | |
273 verify(); | |
274 // Coalesce from high frequency to low | |
275 for( uint i=0; i<_phc._cfg._num_blocks; i++ ) | |
276 coalesce( _phc._blks[i] ); | |
277 | |
278 } | |
279 | |
280 //------------------------------insert_copy_with_overlap----------------------- | |
281 // I am inserting copies to come out of SSA form. In the general case, I am | |
282 // doing a parallel renaming. I'm in the Named world now, so I can't do a | |
283 // general parallel renaming. All the copies now use "names" (live-ranges) | |
284 // to carry values instead of the explicit use-def chains. Suppose I need to | |
285 // insert 2 copies into the same block. They copy L161->L128 and L128->L132. | |
286 // If I insert them in the wrong order then L128 will get clobbered before it | |
287 // can get used by the second copy. This cannot happen in the SSA model; | |
288 // direct use-def chains get me the right value. It DOES happen in the named | |
289 // model so I have to handle the reordering of copies. | |
290 // | |
291 // In general, I need to topo-sort the placed copies to avoid conflicts. | |
292 // Its possible to have a closed cycle of copies (e.g., recirculating the same | |
293 // values around a loop). In this case I need a temp to break the cycle. | |
294 void PhaseAggressiveCoalesce::insert_copy_with_overlap( Block *b, Node *copy, uint dst_name, uint src_name ) { | |
295 | |
296 // Scan backwards for the locations of the last use of the dst_name. | |
297 // I am about to clobber the dst_name, so the copy must be inserted | |
298 // after the last use. Last use is really first-use on a backwards scan. | |
299 uint i = b->end_idx()-1; | |
300 while( 1 ) { | |
301 Node *n = b->_nodes[i]; | |
302 // Check for end of virtual copies; this is also the end of the | |
303 // parallel renaming effort. | |
304 if( n->_idx < _unique ) break; | |
305 uint idx = n->is_Copy(); | |
306 assert( idx || n->is_Con() || n->Opcode() == Op_MachProj, "Only copies during parallel renaming" ); | |
307 if( idx && _phc.Find(n->in(idx)) == dst_name ) break; | |
308 i--; | |
309 } | |
310 uint last_use_idx = i; | |
311 | |
312 // Also search for any kill of src_name that exits the block. | |
313 // Since the copy uses src_name, I have to come before any kill. | |
314 uint kill_src_idx = b->end_idx(); | |
315 // There can be only 1 kill that exits any block and that is | |
316 // the last kill. Thus it is the first kill on a backwards scan. | |
317 i = b->end_idx()-1; | |
318 while( 1 ) { | |
319 Node *n = b->_nodes[i]; | |
320 // Check for end of virtual copies; this is also the end of the | |
321 // parallel renaming effort. | |
322 if( n->_idx < _unique ) break; | |
323 assert( n->is_Copy() || n->is_Con() || n->Opcode() == Op_MachProj, "Only copies during parallel renaming" ); | |
324 if( _phc.Find(n) == src_name ) { | |
325 kill_src_idx = i; | |
326 break; | |
327 } | |
328 i--; | |
329 } | |
330 // Need a temp? Last use of dst comes after the kill of src? | |
331 if( last_use_idx >= kill_src_idx ) { | |
332 // Need to break a cycle with a temp | |
333 uint idx = copy->is_Copy(); | |
334 Node *tmp = copy->clone(); | |
335 _phc.new_lrg(tmp,_phc._maxlrg++); | |
336 // Insert new temp between copy and source | |
337 tmp ->set_req(idx,copy->in(idx)); | |
338 copy->set_req(idx,tmp); | |
339 // Save source in temp early, before source is killed | |
340 b->_nodes.insert(kill_src_idx,tmp); | |
341 _phc._cfg._bbs.map( tmp->_idx, b ); | |
342 last_use_idx++; | |
343 } | |
344 | |
345 // Insert just after last use | |
346 b->_nodes.insert(last_use_idx+1,copy); | |
347 } | |
348 | |
349 //------------------------------insert_copies---------------------------------- | |
350 void PhaseAggressiveCoalesce::insert_copies( Matcher &matcher ) { | |
351 // We do LRGs compressing and fix a liveout data only here since the other | |
352 // place in Split() is guarded by the assert which we never hit. | |
353 _phc.compress_uf_map_for_nodes(); | |
354 // Fix block's liveout data for compressed live ranges. | |
355 for(uint lrg = 1; lrg < _phc._maxlrg; lrg++ ) { | |
356 uint compressed_lrg = _phc.Find(lrg); | |
357 if( lrg != compressed_lrg ) { | |
358 for( uint bidx = 0; bidx < _phc._cfg._num_blocks; bidx++ ) { | |
359 IndexSet *liveout = _phc._live->live(_phc._cfg._blocks[bidx]); | |
360 if( liveout->member(lrg) ) { | |
361 liveout->remove(lrg); | |
362 liveout->insert(compressed_lrg); | |
363 } | |
364 } | |
365 } | |
366 } | |
367 | |
368 // All new nodes added are actual copies to replace virtual copies. | |
369 // Nodes with index less than '_unique' are original, non-virtual Nodes. | |
370 _unique = C->unique(); | |
371 | |
372 for( uint i=0; i<_phc._cfg._num_blocks; i++ ) { | |
373 Block *b = _phc._cfg._blocks[i]; | |
374 uint cnt = b->num_preds(); // Number of inputs to the Phi | |
375 | |
376 for( uint l = 1; l<b->_nodes.size(); l++ ) { | |
377 Node *n = b->_nodes[l]; | |
378 | |
379 // Do not use removed-copies, use copied value instead | |
380 uint ncnt = n->req(); | |
381 for( uint k = 1; k<ncnt; k++ ) { | |
382 Node *copy = n->in(k); | |
383 uint cidx = copy->is_Copy(); | |
384 if( cidx ) { | |
385 Node *def = copy->in(cidx); | |
386 if( _phc.Find(copy) == _phc.Find(def) ) | |
387 n->set_req(k,def); | |
388 } | |
389 } | |
390 | |
391 // Remove any explicit copies that get coalesced. | |
392 uint cidx = n->is_Copy(); | |
393 if( cidx ) { | |
394 Node *def = n->in(cidx); | |
395 if( _phc.Find(n) == _phc.Find(def) ) { | |
396 n->replace_by(def); | |
397 n->set_req(cidx,NULL); | |
398 b->_nodes.remove(l); | |
399 l--; | |
400 continue; | |
401 } | |
402 } | |
403 | |
404 if( n->is_Phi() ) { | |
405 // Get the chosen name for the Phi | |
406 uint phi_name = _phc.Find( n ); | |
407 // Ignore the pre-allocated specials | |
408 if( !phi_name ) continue; | |
409 // Check for mismatch inputs to Phi | |
410 for( uint j = 1; j<cnt; j++ ) { | |
411 Node *m = n->in(j); | |
412 uint src_name = _phc.Find(m); | |
413 if( src_name != phi_name ) { | |
414 Block *pred = _phc._cfg._bbs[b->pred(j)->_idx]; | |
415 Node *copy; | |
416 assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach"); | |
417 // Rematerialize constants instead of copying them | |
418 if( m->is_Mach() && m->as_Mach()->is_Con() && | |
419 m->as_Mach()->rematerialize() ) { | |
420 copy = m->clone(); | |
421 // Insert the copy in the predecessor basic block | |
422 pred->add_inst(copy); | |
423 // Copy any flags as well | |
424 _phc.clone_projs( pred, pred->end_idx(), m, copy, _phc._maxlrg ); | |
425 } else { | |
426 const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()]; | |
427 copy = new (C) MachSpillCopyNode(m,*rm,*rm); | |
428 // Find a good place to insert. Kinda tricky, use a subroutine | |
429 insert_copy_with_overlap(pred,copy,phi_name,src_name); | |
430 } | |
431 // Insert the copy in the use-def chain | |
432 n->set_req( j, copy ); | |
433 _phc._cfg._bbs.map( copy->_idx, pred ); | |
434 // Extend ("register allocate") the names array for the copy. | |
435 _phc._names.extend( copy->_idx, phi_name ); | |
436 } // End of if Phi names do not match | |
437 } // End of for all inputs to Phi | |
438 } else { // End of if Phi | |
439 | |
440 // Now check for 2-address instructions | |
441 uint idx; | |
442 if( n->is_Mach() && (idx=n->as_Mach()->two_adr()) ) { | |
443 // Get the chosen name for the Node | |
444 uint name = _phc.Find( n ); | |
445 assert( name, "no 2-address specials" ); | |
446 // Check for name mis-match on the 2-address input | |
447 Node *m = n->in(idx); | |
448 if( _phc.Find(m) != name ) { | |
449 Node *copy; | |
450 assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach"); | |
451 // At this point it is unsafe to extend live ranges (6550579). | |
452 // Rematerialize only constants as we do for Phi above. | |
453 if( m->is_Mach() && m->as_Mach()->is_Con() && | |
454 m->as_Mach()->rematerialize() ) { | |
455 copy = m->clone(); | |
456 // Insert the copy in the basic block, just before us | |
457 b->_nodes.insert( l++, copy ); | |
458 if( _phc.clone_projs( b, l, m, copy, _phc._maxlrg ) ) | |
459 l++; | |
460 } else { | |
461 const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()]; | |
462 copy = new (C) MachSpillCopyNode( m, *rm, *rm ); | |
463 // Insert the copy in the basic block, just before us | |
464 b->_nodes.insert( l++, copy ); | |
465 } | |
466 // Insert the copy in the use-def chain | |
467 n->set_req(idx, copy ); | |
468 // Extend ("register allocate") the names array for the copy. | |
469 _phc._names.extend( copy->_idx, name ); | |
470 _phc._cfg._bbs.map( copy->_idx, b ); | |
471 } | |
472 | |
473 } // End of is two-adr | |
474 | |
475 // Insert a copy at a debug use for a lrg which has high frequency | |
673 | 476 if( b->_freq < OPTO_DEBUG_SPLIT_FREQ || b->is_uncommon(_phc._cfg._bbs) ) { |
0 | 477 // Walk the debug inputs to the node and check for lrg freq |
478 JVMState* jvms = n->jvms(); | |
479 uint debug_start = jvms ? jvms->debug_start() : 999999; | |
480 uint debug_end = jvms ? jvms->debug_end() : 999999; | |
481 for(uint inpidx = debug_start; inpidx < debug_end; inpidx++) { | |
482 // Do not split monitors; they are only needed for debug table | |
483 // entries and need no code. | |
484 if( jvms->is_monitor_use(inpidx) ) continue; | |
485 Node *inp = n->in(inpidx); | |
486 uint nidx = _phc.n2lidx(inp); | |
487 LRG &lrg = lrgs(nidx); | |
488 | |
489 // If this lrg has a high frequency use/def | |
673 | 490 if( lrg._maxfreq >= _phc.high_frequency_lrg() ) { |
0 | 491 // If the live range is also live out of this block (like it |
492 // would be for a fast/slow idiom), the normal spill mechanism | |
493 // does an excellent job. If it is not live out of this block | |
494 // (like it would be for debug info to uncommon trap) splitting | |
495 // the live range now allows a better allocation in the high | |
496 // frequency blocks. | |
497 // Build_IFG_virtual has converted the live sets to | |
498 // live-IN info, not live-OUT info. | |
499 uint k; | |
500 for( k=0; k < b->_num_succs; k++ ) | |
501 if( _phc._live->live(b->_succs[k])->member( nidx ) ) | |
502 break; // Live in to some successor block? | |
503 if( k < b->_num_succs ) | |
504 continue; // Live out; do not pre-split | |
505 // Split the lrg at this use | |
506 const RegMask *rm = C->matcher()->idealreg2spillmask[inp->ideal_reg()]; | |
507 Node *copy = new (C) MachSpillCopyNode( inp, *rm, *rm ); | |
508 // Insert the copy in the use-def chain | |
509 n->set_req(inpidx, copy ); | |
510 // Insert the copy in the basic block, just before us | |
511 b->_nodes.insert( l++, copy ); | |
512 // Extend ("register allocate") the names array for the copy. | |
513 _phc.new_lrg( copy, _phc._maxlrg++ ); | |
514 _phc._cfg._bbs.map( copy->_idx, b ); | |
515 //tty->print_cr("Split a debug use in Aggressive Coalesce"); | |
516 } // End of if high frequency use/def | |
517 } // End of for all debug inputs | |
518 } // End of if low frequency safepoint | |
519 | |
520 } // End of if Phi | |
521 | |
522 } // End of for all instructions | |
523 } // End of for all blocks | |
524 } | |
525 | |
526 //============================================================================= | |
527 //------------------------------coalesce--------------------------------------- | |
528 // Aggressive (but pessimistic) copy coalescing of a single block | |
529 | |
530 // The following coalesce pass represents a single round of aggressive | |
531 // pessimistic coalesce. "Aggressive" means no attempt to preserve | |
532 // colorability when coalescing. This occasionally means more spills, but | |
533 // it also means fewer rounds of coalescing for better code - and that means | |
534 // faster compiles. | |
535 | |
536 // "Pessimistic" means we do not hit the fixed point in one pass (and we are | |
537 // reaching for the least fixed point to boot). This is typically solved | |
538 // with a few more rounds of coalescing, but the compiler must run fast. We | |
539 // could optimistically coalescing everything touching PhiNodes together | |
540 // into one big live range, then check for self-interference. Everywhere | |
541 // the live range interferes with self it would have to be split. Finding | |
542 // the right split points can be done with some heuristics (based on | |
543 // expected frequency of edges in the live range). In short, it's a real | |
544 // research problem and the timeline is too short to allow such research. | |
545 // Further thoughts: (1) build the LR in a pass, (2) find self-interference | |
546 // in another pass, (3) per each self-conflict, split, (4) split by finding | |
547 // the low-cost cut (min-cut) of the LR, (5) edges in the LR are weighted | |
548 // according to the GCM algorithm (or just exec freq on CFG edges). | |
549 | |
550 void PhaseAggressiveCoalesce::coalesce( Block *b ) { | |
551 // Copies are still "virtual" - meaning we have not made them explicitly | |
552 // copies. Instead, Phi functions of successor blocks have mis-matched | |
553 // live-ranges. If I fail to coalesce, I'll have to insert a copy to line | |
554 // up the live-ranges. Check for Phis in successor blocks. | |
555 uint i; | |
556 for( i=0; i<b->_num_succs; i++ ) { | |
557 Block *bs = b->_succs[i]; | |
558 // Find index of 'b' in 'bs' predecessors | |
559 uint j=1; | |
560 while( _phc._cfg._bbs[bs->pred(j)->_idx] != b ) j++; | |
561 // Visit all the Phis in successor block | |
562 for( uint k = 1; k<bs->_nodes.size(); k++ ) { | |
563 Node *n = bs->_nodes[k]; | |
564 if( !n->is_Phi() ) break; | |
565 combine_these_two( n, n->in(j) ); | |
566 } | |
567 } // End of for all successor blocks | |
568 | |
569 | |
570 // Check _this_ block for 2-address instructions and copies. | |
571 uint cnt = b->end_idx(); | |
572 for( i = 1; i<cnt; i++ ) { | |
573 Node *n = b->_nodes[i]; | |
574 uint idx; | |
575 // 2-address instructions have a virtual Copy matching their input | |
576 // to their output | |
577 if( n->is_Mach() && (idx = n->as_Mach()->two_adr()) ) { | |
578 MachNode *mach = n->as_Mach(); | |
579 combine_these_two( mach, mach->in(idx) ); | |
580 } | |
581 } // End of for all instructions in block | |
582 } | |
583 | |
584 //============================================================================= | |
585 //------------------------------PhaseConservativeCoalesce---------------------- | |
586 PhaseConservativeCoalesce::PhaseConservativeCoalesce( PhaseChaitin &chaitin ) : PhaseCoalesce(chaitin) { | |
587 _ulr.initialize(_phc._maxlrg); | |
588 } | |
589 | |
590 //------------------------------verify----------------------------------------- | |
591 void PhaseConservativeCoalesce::verify() { | |
592 #ifdef ASSERT | |
593 _phc.set_was_low(); | |
594 #endif | |
595 } | |
596 | |
597 //------------------------------union_helper----------------------------------- | |
598 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 ) { | |
599 // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the | |
600 // union-find tree | |
601 _phc.Union( lr1_node, lr2_node ); | |
602 | |
603 // Single-def live range ONLY if both live ranges are single-def. | |
604 // If both are single def, then src_def powers one live range | |
605 // and def_copy powers the other. After merging, src_def powers | |
606 // the combined live range. | |
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607 lrgs(lr1)._def = (lrgs(lr1).is_multidef() || |
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608 lrgs(lr2).is_multidef() ) |
0 | 609 ? NodeSentinel : src_def; |
610 lrgs(lr2)._def = NULL; // No def for lrg 2 | |
611 lrgs(lr2).Clear(); // Force empty mask for LRG 2 | |
612 //lrgs(lr2)._size = 0; // Live-range 2 goes dead | |
613 lrgs(lr1)._is_oop |= lrgs(lr2)._is_oop; | |
614 lrgs(lr2)._is_oop = 0; // In particular, not an oop for GC info | |
615 | |
616 if (lrgs(lr1)._maxfreq < lrgs(lr2)._maxfreq) | |
617 lrgs(lr1)._maxfreq = lrgs(lr2)._maxfreq; | |
618 | |
619 // Copy original value instead. Intermediate copies go dead, and | |
620 // the dst_copy becomes useless. | |
621 int didx = dst_copy->is_Copy(); | |
622 dst_copy->set_req( didx, src_def ); | |
623 // Add copy to free list | |
624 // _phc.free_spillcopy(b->_nodes[bindex]); | |
625 assert( b->_nodes[bindex] == dst_copy, "" ); | |
626 dst_copy->replace_by( dst_copy->in(didx) ); | |
627 dst_copy->set_req( didx, NULL); | |
628 b->_nodes.remove(bindex); | |
629 if( bindex < b->_ihrp_index ) b->_ihrp_index--; | |
630 if( bindex < b->_fhrp_index ) b->_fhrp_index--; | |
631 | |
632 // Stretched lr1; add it to liveness of intermediate blocks | |
633 Block *b2 = _phc._cfg._bbs[src_copy->_idx]; | |
634 while( b != b2 ) { | |
635 b = _phc._cfg._bbs[b->pred(1)->_idx]; | |
636 _phc._live->live(b)->insert(lr1); | |
637 } | |
638 } | |
639 | |
640 //------------------------------compute_separating_interferences--------------- | |
641 // Factored code from copy_copy that computes extra interferences from | |
642 // lengthening a live range by double-coalescing. | |
643 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 ) { | |
644 | |
645 assert(!lrgs(lr1)._fat_proj, "cannot coalesce fat_proj"); | |
646 assert(!lrgs(lr2)._fat_proj, "cannot coalesce fat_proj"); | |
647 Node *prev_copy = dst_copy->in(dst_copy->is_Copy()); | |
648 Block *b2 = b; | |
649 uint bindex2 = bindex; | |
650 while( 1 ) { | |
651 // Find previous instruction | |
652 bindex2--; // Chain backwards 1 instruction | |
653 while( bindex2 == 0 ) { // At block start, find prior block | |
654 assert( b2->num_preds() == 2, "cannot double coalesce across c-flow" ); | |
655 b2 = _phc._cfg._bbs[b2->pred(1)->_idx]; | |
656 bindex2 = b2->end_idx()-1; | |
657 } | |
658 // Get prior instruction | |
659 assert(bindex2 < b2->_nodes.size(), "index out of bounds"); | |
660 Node *x = b2->_nodes[bindex2]; | |
661 if( x == prev_copy ) { // Previous copy in copy chain? | |
662 if( prev_copy == src_copy)// Found end of chain and all interferences | |
663 break; // So break out of loop | |
664 // Else work back one in copy chain | |
665 prev_copy = prev_copy->in(prev_copy->is_Copy()); | |
666 } else { // Else collect interferences | |
667 uint lidx = _phc.Find(x); | |
668 // Found another def of live-range being stretched? | |
669 if( lidx == lr1 ) return max_juint; | |
670 if( lidx == lr2 ) return max_juint; | |
671 | |
672 // If we attempt to coalesce across a bound def | |
673 if( lrgs(lidx).is_bound() ) { | |
674 // Do not let the coalesced LRG expect to get the bound color | |
675 rm.SUBTRACT( lrgs(lidx).mask() ); | |
676 // Recompute rm_size | |
677 rm_size = rm.Size(); | |
678 //if( rm._flags ) rm_size += 1000000; | |
679 if( reg_degree >= rm_size ) return max_juint; | |
680 } | |
681 if( rm.overlap(lrgs(lidx).mask()) ) { | |
682 // Insert lidx into union LRG; returns TRUE if actually inserted | |
683 if( _ulr.insert(lidx) ) { | |
684 // Infinite-stack neighbors do not alter colorability, as they | |
685 // can always color to some other color. | |
686 if( !lrgs(lidx).mask().is_AllStack() ) { | |
687 // If this coalesce will make any new neighbor uncolorable, | |
688 // do not coalesce. | |
689 if( lrgs(lidx).just_lo_degree() ) | |
690 return max_juint; | |
691 // Bump our degree | |
692 if( ++reg_degree >= rm_size ) | |
693 return max_juint; | |
694 } // End of if not infinite-stack neighbor | |
695 } // End of if actually inserted | |
696 } // End of if live range overlaps | |
605 | 697 } // End of else collect interferences for 1 node |
698 } // End of while forever, scan back for interferences | |
0 | 699 return reg_degree; |
700 } | |
701 | |
702 //------------------------------update_ifg------------------------------------- | |
703 void PhaseConservativeCoalesce::update_ifg(uint lr1, uint lr2, IndexSet *n_lr1, IndexSet *n_lr2) { | |
704 // Some original neighbors of lr1 might have gone away | |
705 // because the constrained register mask prevented them. | |
706 // Remove lr1 from such neighbors. | |
707 IndexSetIterator one(n_lr1); | |
708 uint neighbor; | |
709 LRG &lrg1 = lrgs(lr1); | |
710 while ((neighbor = one.next()) != 0) | |
711 if( !_ulr.member(neighbor) ) | |
712 if( _phc._ifg->neighbors(neighbor)->remove(lr1) ) | |
713 lrgs(neighbor).inc_degree( -lrg1.compute_degree(lrgs(neighbor)) ); | |
714 | |
715 | |
716 // lr2 is now called (coalesced into) lr1. | |
717 // Remove lr2 from the IFG. | |
718 IndexSetIterator two(n_lr2); | |
719 LRG &lrg2 = lrgs(lr2); | |
720 while ((neighbor = two.next()) != 0) | |
721 if( _phc._ifg->neighbors(neighbor)->remove(lr2) ) | |
722 lrgs(neighbor).inc_degree( -lrg2.compute_degree(lrgs(neighbor)) ); | |
723 | |
724 // Some neighbors of intermediate copies now interfere with the | |
725 // combined live range. | |
726 IndexSetIterator three(&_ulr); | |
727 while ((neighbor = three.next()) != 0) | |
728 if( _phc._ifg->neighbors(neighbor)->insert(lr1) ) | |
729 lrgs(neighbor).inc_degree( lrg1.compute_degree(lrgs(neighbor)) ); | |
730 } | |
731 | |
732 //------------------------------record_bias------------------------------------ | |
733 static void record_bias( const PhaseIFG *ifg, int lr1, int lr2 ) { | |
734 // Tag copy bias here | |
735 if( !ifg->lrgs(lr1)._copy_bias ) | |
736 ifg->lrgs(lr1)._copy_bias = lr2; | |
737 if( !ifg->lrgs(lr2)._copy_bias ) | |
738 ifg->lrgs(lr2)._copy_bias = lr1; | |
739 } | |
740 | |
741 //------------------------------copy_copy-------------------------------------- | |
742 // See if I can coalesce a series of multiple copies together. I need the | |
743 // final dest copy and the original src copy. They can be the same Node. | |
744 // Compute the compatible register masks. | |
745 bool PhaseConservativeCoalesce::copy_copy( Node *dst_copy, Node *src_copy, Block *b, uint bindex ) { | |
746 | |
747 if( !dst_copy->is_SpillCopy() ) return false; | |
748 if( !src_copy->is_SpillCopy() ) return false; | |
749 Node *src_def = src_copy->in(src_copy->is_Copy()); | |
750 uint lr1 = _phc.Find(dst_copy); | |
751 uint lr2 = _phc.Find(src_def ); | |
752 | |
753 // Same live ranges already? | |
754 if( lr1 == lr2 ) return false; | |
755 | |
756 // Interfere? | |
757 if( _phc._ifg->test_edge_sq( lr1, lr2 ) ) return false; | |
758 | |
759 // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK. | |
760 if( !lrgs(lr1)._is_oop && lrgs(lr2)._is_oop ) // not an oop->int cast | |
761 return false; | |
762 | |
763 // Coalescing between an aligned live range and a mis-aligned live range? | |
764 // No, no! Alignment changes how we count degree. | |
765 if( lrgs(lr1)._fat_proj != lrgs(lr2)._fat_proj ) | |
766 return false; | |
767 | |
768 // Sort; use smaller live-range number | |
769 Node *lr1_node = dst_copy; | |
770 Node *lr2_node = src_def; | |
771 if( lr1 > lr2 ) { | |
772 uint tmp = lr1; lr1 = lr2; lr2 = tmp; | |
773 lr1_node = src_def; lr2_node = dst_copy; | |
774 } | |
775 | |
776 // Check for compatibility of the 2 live ranges by | |
777 // intersecting their allowed register sets. | |
778 RegMask rm = lrgs(lr1).mask(); | |
779 rm.AND(lrgs(lr2).mask()); | |
780 // Number of bits free | |
781 uint rm_size = rm.Size(); | |
782 | |
783 // If we can use any stack slot, then effective size is infinite | |
784 if( rm.is_AllStack() ) rm_size += 1000000; | |
785 // Incompatible masks, no way to coalesce | |
786 if( rm_size == 0 ) return false; | |
787 | |
788 // Another early bail-out test is when we are double-coalescing and the | |
605 | 789 // 2 copies are separated by some control flow. |
0 | 790 if( dst_copy != src_copy ) { |
791 Block *src_b = _phc._cfg._bbs[src_copy->_idx]; | |
792 Block *b2 = b; | |
793 while( b2 != src_b ) { | |
794 if( b2->num_preds() > 2 ){// Found merge-point | |
795 _phc._lost_opp_cflow_coalesce++; | |
796 // extra record_bias commented out because Chris believes it is not | |
797 // productive. Since we can record only 1 bias, we want to choose one | |
798 // that stands a chance of working and this one probably does not. | |
799 //record_bias( _phc._lrgs, lr1, lr2 ); | |
800 return false; // To hard to find all interferences | |
801 } | |
802 b2 = _phc._cfg._bbs[b2->pred(1)->_idx]; | |
803 } | |
804 } | |
805 | |
806 // Union the two interference sets together into '_ulr' | |
807 uint reg_degree = _ulr.lrg_union( lr1, lr2, rm_size, _phc._ifg, rm ); | |
808 | |
809 if( reg_degree >= rm_size ) { | |
810 record_bias( _phc._ifg, lr1, lr2 ); | |
811 return false; | |
812 } | |
813 | |
814 // Now I need to compute all the interferences between dst_copy and | |
815 // src_copy. I'm not willing visit the entire interference graph, so | |
816 // I limit my search to things in dst_copy's block or in a straight | |
817 // line of previous blocks. I give up at merge points or when I get | |
818 // more interferences than my degree. I can stop when I find src_copy. | |
819 if( dst_copy != src_copy ) { | |
820 reg_degree = compute_separating_interferences(dst_copy, src_copy, b, bindex, rm, rm_size, reg_degree, lr1, lr2 ); | |
821 if( reg_degree == max_juint ) { | |
822 record_bias( _phc._ifg, lr1, lr2 ); | |
823 return false; | |
824 } | |
825 } // End of if dst_copy & src_copy are different | |
826 | |
827 | |
828 // ---- THE COMBINED LRG IS COLORABLE ---- | |
829 | |
830 // YEAH - Now coalesce this copy away | |
831 assert( lrgs(lr1).num_regs() == lrgs(lr2).num_regs(), "" ); | |
832 | |
833 IndexSet *n_lr1 = _phc._ifg->neighbors(lr1); | |
834 IndexSet *n_lr2 = _phc._ifg->neighbors(lr2); | |
835 | |
836 // Update the interference graph | |
837 update_ifg(lr1, lr2, n_lr1, n_lr2); | |
838 | |
839 _ulr.remove(lr1); | |
840 | |
841 // Uncomment the following code to trace Coalescing in great detail. | |
842 // | |
843 //if (false) { | |
844 // tty->cr(); | |
845 // tty->print_cr("#######################################"); | |
846 // tty->print_cr("union %d and %d", lr1, lr2); | |
847 // n_lr1->dump(); | |
848 // n_lr2->dump(); | |
849 // tty->print_cr("resulting set is"); | |
850 // _ulr.dump(); | |
851 //} | |
852 | |
853 // Replace n_lr1 with the new combined live range. _ulr will use | |
854 // n_lr1's old memory on the next iteration. n_lr2 is cleared to | |
855 // send its internal memory to the free list. | |
856 _ulr.swap(n_lr1); | |
857 _ulr.clear(); | |
858 n_lr2->clear(); | |
859 | |
860 lrgs(lr1).set_degree( _phc._ifg->effective_degree(lr1) ); | |
861 lrgs(lr2).set_degree( 0 ); | |
862 | |
863 // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the | |
864 // union-find tree | |
865 union_helper( lr1_node, lr2_node, lr1, lr2, src_def, dst_copy, src_copy, b, bindex ); | |
866 // Combine register restrictions | |
867 lrgs(lr1).set_mask(rm); | |
868 lrgs(lr1).compute_set_mask_size(); | |
869 lrgs(lr1)._cost += lrgs(lr2)._cost; | |
870 lrgs(lr1)._area += lrgs(lr2)._area; | |
871 | |
872 // While its uncommon to successfully coalesce live ranges that started out | |
873 // being not-lo-degree, it can happen. In any case the combined coalesced | |
874 // live range better Simplify nicely. | |
875 lrgs(lr1)._was_lo = 1; | |
876 | |
877 // kinda expensive to do all the time | |
878 //tty->print_cr("warning: slow verify happening"); | |
879 //_phc._ifg->verify( &_phc ); | |
880 return true; | |
881 } | |
882 | |
883 //------------------------------coalesce--------------------------------------- | |
884 // Conservative (but pessimistic) copy coalescing of a single block | |
885 void PhaseConservativeCoalesce::coalesce( Block *b ) { | |
886 // Bail out on infrequent blocks | |
887 if( b->is_uncommon(_phc._cfg._bbs) ) | |
888 return; | |
889 // Check this block for copies. | |
890 for( uint i = 1; i<b->end_idx(); i++ ) { | |
891 // Check for actual copies on inputs. Coalesce a copy into its | |
892 // input if use and copy's input are compatible. | |
893 Node *copy1 = b->_nodes[i]; | |
894 uint idx1 = copy1->is_Copy(); | |
895 if( !idx1 ) continue; // Not a copy | |
896 | |
897 if( copy_copy(copy1,copy1,b,i) ) { | |
898 i--; // Retry, same location in block | |
899 PhaseChaitin::_conserv_coalesce++; // Collect stats on success | |
900 continue; | |
901 } | |
902 | |
903 /* do not attempt pairs. About 1/2 of all pairs can be removed by | |
904 post-alloc. The other set are too few to bother. | |
905 Node *copy2 = copy1->in(idx1); | |
906 uint idx2 = copy2->is_Copy(); | |
907 if( !idx2 ) continue; | |
908 if( copy_copy(copy1,copy2,b,i) ) { | |
909 i--; // Retry, same location in block | |
910 PhaseChaitin::_conserv_coalesce_pair++; // Collect stats on success | |
911 continue; | |
912 } | |
913 */ | |
914 } | |
915 } |