Mercurial > hg > truffle
annotate src/share/vm/opto/coalesce.cpp @ 3842:c7b60b601eb4
7069452: Cleanup NodeFlags
Summary: Remove flags which duplicate information in Node::NodeClasses.
Reviewed-by: never
| author | kvn |
|---|---|
| date | Wed, 27 Jul 2011 17:28:36 -0700 |
| parents | f95d63e2154a |
| children | 8373c19be854 |
| rev | line source |
|---|---|
| 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 * | |
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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 } |