1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/opto/coalesce.cpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,915 @@
1.4 +/*
1.5 + * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "incls/_precompiled.incl"
1.29 +#include "incls/_coalesce.cpp.incl"
1.30 +
1.31 +//=============================================================================
1.32 +//------------------------------reset_uf_map-----------------------------------
1.33 +void PhaseChaitin::reset_uf_map( uint maxlrg ) {
1.34 + _maxlrg = maxlrg;
1.35 + // Force the Union-Find mapping to be at least this large
1.36 + _uf_map.extend(_maxlrg,0);
1.37 + // Initialize it to be the ID mapping.
1.38 + for( uint i=0; i<_maxlrg; i++ )
1.39 + _uf_map.map(i,i);
1.40 +}
1.41 +
1.42 +//------------------------------compress_uf_map--------------------------------
1.43 +// Make all Nodes map directly to their final live range; no need for
1.44 +// the Union-Find mapping after this call.
1.45 +void PhaseChaitin::compress_uf_map_for_nodes( ) {
1.46 + // For all Nodes, compress mapping
1.47 + uint unique = _names.Size();
1.48 + for( uint i=0; i<unique; i++ ) {
1.49 + uint lrg = _names[i];
1.50 + uint compressed_lrg = Find(lrg);
1.51 + if( lrg != compressed_lrg )
1.52 + _names.map(i,compressed_lrg);
1.53 + }
1.54 +}
1.55 +
1.56 +//------------------------------Find-------------------------------------------
1.57 +// Straight out of Tarjan's union-find algorithm
1.58 +uint PhaseChaitin::Find_compress( uint lrg ) {
1.59 + uint cur = lrg;
1.60 + uint next = _uf_map[cur];
1.61 + while( next != cur ) { // Scan chain of equivalences
1.62 + assert( next < cur, "always union smaller" );
1.63 + cur = next; // until find a fixed-point
1.64 + next = _uf_map[cur];
1.65 + }
1.66 + // Core of union-find algorithm: update chain of
1.67 + // equivalences to be equal to the root.
1.68 + while( lrg != next ) {
1.69 + uint tmp = _uf_map[lrg];
1.70 + _uf_map.map(lrg, next);
1.71 + lrg = tmp;
1.72 + }
1.73 + return lrg;
1.74 +}
1.75 +
1.76 +//------------------------------Find-------------------------------------------
1.77 +// Straight out of Tarjan's union-find algorithm
1.78 +uint PhaseChaitin::Find_compress( const Node *n ) {
1.79 + uint lrg = Find_compress(_names[n->_idx]);
1.80 + _names.map(n->_idx,lrg);
1.81 + return lrg;
1.82 +}
1.83 +
1.84 +//------------------------------Find_const-------------------------------------
1.85 +// Like Find above, but no path compress, so bad asymptotic behavior
1.86 +uint PhaseChaitin::Find_const( uint lrg ) const {
1.87 + if( !lrg ) return lrg; // Ignore the zero LRG
1.88 + // Off the end? This happens during debugging dumps when you got
1.89 + // brand new live ranges but have not told the allocator yet.
1.90 + if( lrg >= _maxlrg ) return lrg;
1.91 + uint next = _uf_map[lrg];
1.92 + while( next != lrg ) { // Scan chain of equivalences
1.93 + assert( next < lrg, "always union smaller" );
1.94 + lrg = next; // until find a fixed-point
1.95 + next = _uf_map[lrg];
1.96 + }
1.97 + return next;
1.98 +}
1.99 +
1.100 +//------------------------------Find-------------------------------------------
1.101 +// Like Find above, but no path compress, so bad asymptotic behavior
1.102 +uint PhaseChaitin::Find_const( const Node *n ) const {
1.103 + if( n->_idx >= _names.Size() ) return 0; // not mapped, usual for debug dump
1.104 + return Find_const( _names[n->_idx] );
1.105 +}
1.106 +
1.107 +//------------------------------Union------------------------------------------
1.108 +// union 2 sets together.
1.109 +void PhaseChaitin::Union( const Node *src_n, const Node *dst_n ) {
1.110 + uint src = Find(src_n);
1.111 + uint dst = Find(dst_n);
1.112 + assert( src, "" );
1.113 + assert( dst, "" );
1.114 + assert( src < _maxlrg, "oob" );
1.115 + assert( dst < _maxlrg, "oob" );
1.116 + assert( src < dst, "always union smaller" );
1.117 + _uf_map.map(dst,src);
1.118 +}
1.119 +
1.120 +//------------------------------new_lrg----------------------------------------
1.121 +void PhaseChaitin::new_lrg( const Node *x, uint lrg ) {
1.122 + // Make the Node->LRG mapping
1.123 + _names.extend(x->_idx,lrg);
1.124 + // Make the Union-Find mapping an identity function
1.125 + _uf_map.extend(lrg,lrg);
1.126 +}
1.127 +
1.128 +//------------------------------clone_projs------------------------------------
1.129 +// After cloning some rematierialized instruction, clone any MachProj's that
1.130 +// follow it. Example: Intel zero is XOR, kills flags. Sparc FP constants
1.131 +// use G3 as an address temp.
1.132 +int PhaseChaitin::clone_projs( Block *b, uint idx, Node *con, Node *copy, uint &maxlrg ) {
1.133 + Block *bcon = _cfg._bbs[con->_idx];
1.134 + uint cindex = bcon->find_node(con);
1.135 + Node *con_next = bcon->_nodes[cindex+1];
1.136 + if( con_next->in(0) != con || con_next->Opcode() != Op_MachProj )
1.137 + return false; // No MachProj's follow
1.138 +
1.139 + // Copy kills after the cloned constant
1.140 + Node *kills = con_next->clone();
1.141 + kills->set_req( 0, copy );
1.142 + b->_nodes.insert( idx, kills );
1.143 + _cfg._bbs.map( kills->_idx, b );
1.144 + new_lrg( kills, maxlrg++ );
1.145 + return true;
1.146 +}
1.147 +
1.148 +//------------------------------compact----------------------------------------
1.149 +// Renumber the live ranges to compact them. Makes the IFG smaller.
1.150 +void PhaseChaitin::compact() {
1.151 + // Current the _uf_map contains a series of short chains which are headed
1.152 + // by a self-cycle. All the chains run from big numbers to little numbers.
1.153 + // The Find() call chases the chains & shortens them for the next Find call.
1.154 + // We are going to change this structure slightly. Numbers above a moving
1.155 + // wave 'i' are unchanged. Numbers below 'j' point directly to their
1.156 + // compacted live range with no further chaining. There are no chains or
1.157 + // cycles below 'i', so the Find call no longer works.
1.158 + uint j=1;
1.159 + uint i;
1.160 + for( i=1; i < _maxlrg; i++ ) {
1.161 + uint lr = _uf_map[i];
1.162 + // Ignore unallocated live ranges
1.163 + if( !lr ) continue;
1.164 + assert( lr <= i, "" );
1.165 + _uf_map.map(i, ( lr == i ) ? j++ : _uf_map[lr]);
1.166 + }
1.167 + if( false ) // PrintOptoCompactLiveRanges
1.168 + printf("Compacted %d LRs from %d\n",i-j,i);
1.169 + // Now change the Node->LR mapping to reflect the compacted names
1.170 + uint unique = _names.Size();
1.171 + for( i=0; i<unique; i++ )
1.172 + _names.map(i,_uf_map[_names[i]]);
1.173 +
1.174 + // Reset the Union-Find mapping
1.175 + reset_uf_map(j);
1.176 +
1.177 +}
1.178 +
1.179 +//=============================================================================
1.180 +//------------------------------Dump-------------------------------------------
1.181 +#ifndef PRODUCT
1.182 +void PhaseCoalesce::dump( Node *n ) const {
1.183 + // Being a const function means I cannot use 'Find'
1.184 + uint r = _phc.Find(n);
1.185 + tty->print("L%d/N%d ",r,n->_idx);
1.186 +}
1.187 +
1.188 +//------------------------------dump-------------------------------------------
1.189 +void PhaseCoalesce::dump() const {
1.190 + // I know I have a block layout now, so I can print blocks in a loop
1.191 + for( uint i=0; i<_phc._cfg._num_blocks; i++ ) {
1.192 + uint j;
1.193 + Block *b = _phc._cfg._blocks[i];
1.194 + // Print a nice block header
1.195 + tty->print("B%d: ",b->_pre_order);
1.196 + for( j=1; j<b->num_preds(); j++ )
1.197 + tty->print("B%d ", _phc._cfg._bbs[b->pred(j)->_idx]->_pre_order);
1.198 + tty->print("-> ");
1.199 + for( j=0; j<b->_num_succs; j++ )
1.200 + tty->print("B%d ",b->_succs[j]->_pre_order);
1.201 + tty->print(" IDom: B%d/#%d\n", b->_idom ? b->_idom->_pre_order : 0, b->_dom_depth);
1.202 + uint cnt = b->_nodes.size();
1.203 + for( j=0; j<cnt; j++ ) {
1.204 + Node *n = b->_nodes[j];
1.205 + dump( n );
1.206 + tty->print("\t%s\t",n->Name());
1.207 +
1.208 + // Dump the inputs
1.209 + uint k; // Exit value of loop
1.210 + for( k=0; k<n->req(); k++ ) // For all required inputs
1.211 + if( n->in(k) ) dump( n->in(k) );
1.212 + else tty->print("_ ");
1.213 + int any_prec = 0;
1.214 + for( ; k<n->len(); k++ ) // For all precedence inputs
1.215 + if( n->in(k) ) {
1.216 + if( !any_prec++ ) tty->print(" |");
1.217 + dump( n->in(k) );
1.218 + }
1.219 +
1.220 + // Dump node-specific info
1.221 + n->dump_spec(tty);
1.222 + tty->print("\n");
1.223 +
1.224 + }
1.225 + tty->print("\n");
1.226 + }
1.227 +}
1.228 +#endif
1.229 +
1.230 +//------------------------------combine_these_two------------------------------
1.231 +// Combine the live ranges def'd by these 2 Nodes. N2 is an input to N1.
1.232 +void PhaseCoalesce::combine_these_two( Node *n1, Node *n2 ) {
1.233 + uint lr1 = _phc.Find(n1);
1.234 + uint lr2 = _phc.Find(n2);
1.235 + if( lr1 != lr2 && // Different live ranges already AND
1.236 + !_phc._ifg->test_edge_sq( lr1, lr2 ) ) { // Do not interfere
1.237 + LRG *lrg1 = &_phc.lrgs(lr1);
1.238 + LRG *lrg2 = &_phc.lrgs(lr2);
1.239 + // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK.
1.240 +
1.241 + // Now, why is int->oop OK? We end up declaring a raw-pointer as an oop
1.242 + // and in general that's a bad thing. However, int->oop conversions only
1.243 + // happen at GC points, so the lifetime of the misclassified raw-pointer
1.244 + // is from the CheckCastPP (that converts it to an oop) backwards up
1.245 + // through a merge point and into the slow-path call, and around the
1.246 + // diamond up to the heap-top check and back down into the slow-path call.
1.247 + // The misclassified raw pointer is NOT live across the slow-path call,
1.248 + // and so does not appear in any GC info, so the fact that it is
1.249 + // misclassified is OK.
1.250 +
1.251 + if( (lrg1->_is_oop || !lrg2->_is_oop) && // not an oop->int cast AND
1.252 + // Compatible final mask
1.253 + lrg1->mask().overlap( lrg2->mask() ) ) {
1.254 + // Merge larger into smaller.
1.255 + if( lr1 > lr2 ) {
1.256 + uint tmp = lr1; lr1 = lr2; lr2 = tmp;
1.257 + Node *n = n1; n1 = n2; n2 = n;
1.258 + LRG *ltmp = lrg1; lrg1 = lrg2; lrg2 = ltmp;
1.259 + }
1.260 + // Union lr2 into lr1
1.261 + _phc.Union( n1, n2 );
1.262 + if (lrg1->_maxfreq < lrg2->_maxfreq)
1.263 + lrg1->_maxfreq = lrg2->_maxfreq;
1.264 + // Merge in the IFG
1.265 + _phc._ifg->Union( lr1, lr2 );
1.266 + // Combine register restrictions
1.267 + lrg1->AND(lrg2->mask());
1.268 + }
1.269 + }
1.270 +}
1.271 +
1.272 +//------------------------------coalesce_driver--------------------------------
1.273 +// Copy coalescing
1.274 +void PhaseCoalesce::coalesce_driver( ) {
1.275 +
1.276 + verify();
1.277 + // Coalesce from high frequency to low
1.278 + for( uint i=0; i<_phc._cfg._num_blocks; i++ )
1.279 + coalesce( _phc._blks[i] );
1.280 +
1.281 +}
1.282 +
1.283 +//------------------------------insert_copy_with_overlap-----------------------
1.284 +// I am inserting copies to come out of SSA form. In the general case, I am
1.285 +// doing a parallel renaming. I'm in the Named world now, so I can't do a
1.286 +// general parallel renaming. All the copies now use "names" (live-ranges)
1.287 +// to carry values instead of the explicit use-def chains. Suppose I need to
1.288 +// insert 2 copies into the same block. They copy L161->L128 and L128->L132.
1.289 +// If I insert them in the wrong order then L128 will get clobbered before it
1.290 +// can get used by the second copy. This cannot happen in the SSA model;
1.291 +// direct use-def chains get me the right value. It DOES happen in the named
1.292 +// model so I have to handle the reordering of copies.
1.293 +//
1.294 +// In general, I need to topo-sort the placed copies to avoid conflicts.
1.295 +// Its possible to have a closed cycle of copies (e.g., recirculating the same
1.296 +// values around a loop). In this case I need a temp to break the cycle.
1.297 +void PhaseAggressiveCoalesce::insert_copy_with_overlap( Block *b, Node *copy, uint dst_name, uint src_name ) {
1.298 +
1.299 + // Scan backwards for the locations of the last use of the dst_name.
1.300 + // I am about to clobber the dst_name, so the copy must be inserted
1.301 + // after the last use. Last use is really first-use on a backwards scan.
1.302 + uint i = b->end_idx()-1;
1.303 + while( 1 ) {
1.304 + Node *n = b->_nodes[i];
1.305 + // Check for end of virtual copies; this is also the end of the
1.306 + // parallel renaming effort.
1.307 + if( n->_idx < _unique ) break;
1.308 + uint idx = n->is_Copy();
1.309 + assert( idx || n->is_Con() || n->Opcode() == Op_MachProj, "Only copies during parallel renaming" );
1.310 + if( idx && _phc.Find(n->in(idx)) == dst_name ) break;
1.311 + i--;
1.312 + }
1.313 + uint last_use_idx = i;
1.314 +
1.315 + // Also search for any kill of src_name that exits the block.
1.316 + // Since the copy uses src_name, I have to come before any kill.
1.317 + uint kill_src_idx = b->end_idx();
1.318 + // There can be only 1 kill that exits any block and that is
1.319 + // the last kill. Thus it is the first kill on a backwards scan.
1.320 + i = b->end_idx()-1;
1.321 + while( 1 ) {
1.322 + Node *n = b->_nodes[i];
1.323 + // Check for end of virtual copies; this is also the end of the
1.324 + // parallel renaming effort.
1.325 + if( n->_idx < _unique ) break;
1.326 + assert( n->is_Copy() || n->is_Con() || n->Opcode() == Op_MachProj, "Only copies during parallel renaming" );
1.327 + if( _phc.Find(n) == src_name ) {
1.328 + kill_src_idx = i;
1.329 + break;
1.330 + }
1.331 + i--;
1.332 + }
1.333 + // Need a temp? Last use of dst comes after the kill of src?
1.334 + if( last_use_idx >= kill_src_idx ) {
1.335 + // Need to break a cycle with a temp
1.336 + uint idx = copy->is_Copy();
1.337 + Node *tmp = copy->clone();
1.338 + _phc.new_lrg(tmp,_phc._maxlrg++);
1.339 + // Insert new temp between copy and source
1.340 + tmp ->set_req(idx,copy->in(idx));
1.341 + copy->set_req(idx,tmp);
1.342 + // Save source in temp early, before source is killed
1.343 + b->_nodes.insert(kill_src_idx,tmp);
1.344 + _phc._cfg._bbs.map( tmp->_idx, b );
1.345 + last_use_idx++;
1.346 + }
1.347 +
1.348 + // Insert just after last use
1.349 + b->_nodes.insert(last_use_idx+1,copy);
1.350 +}
1.351 +
1.352 +//------------------------------insert_copies----------------------------------
1.353 +void PhaseAggressiveCoalesce::insert_copies( Matcher &matcher ) {
1.354 + // We do LRGs compressing and fix a liveout data only here since the other
1.355 + // place in Split() is guarded by the assert which we never hit.
1.356 + _phc.compress_uf_map_for_nodes();
1.357 + // Fix block's liveout data for compressed live ranges.
1.358 + for(uint lrg = 1; lrg < _phc._maxlrg; lrg++ ) {
1.359 + uint compressed_lrg = _phc.Find(lrg);
1.360 + if( lrg != compressed_lrg ) {
1.361 + for( uint bidx = 0; bidx < _phc._cfg._num_blocks; bidx++ ) {
1.362 + IndexSet *liveout = _phc._live->live(_phc._cfg._blocks[bidx]);
1.363 + if( liveout->member(lrg) ) {
1.364 + liveout->remove(lrg);
1.365 + liveout->insert(compressed_lrg);
1.366 + }
1.367 + }
1.368 + }
1.369 + }
1.370 +
1.371 + // All new nodes added are actual copies to replace virtual copies.
1.372 + // Nodes with index less than '_unique' are original, non-virtual Nodes.
1.373 + _unique = C->unique();
1.374 +
1.375 + for( uint i=0; i<_phc._cfg._num_blocks; i++ ) {
1.376 + Block *b = _phc._cfg._blocks[i];
1.377 + uint cnt = b->num_preds(); // Number of inputs to the Phi
1.378 +
1.379 + for( uint l = 1; l<b->_nodes.size(); l++ ) {
1.380 + Node *n = b->_nodes[l];
1.381 +
1.382 + // Do not use removed-copies, use copied value instead
1.383 + uint ncnt = n->req();
1.384 + for( uint k = 1; k<ncnt; k++ ) {
1.385 + Node *copy = n->in(k);
1.386 + uint cidx = copy->is_Copy();
1.387 + if( cidx ) {
1.388 + Node *def = copy->in(cidx);
1.389 + if( _phc.Find(copy) == _phc.Find(def) )
1.390 + n->set_req(k,def);
1.391 + }
1.392 + }
1.393 +
1.394 + // Remove any explicit copies that get coalesced.
1.395 + uint cidx = n->is_Copy();
1.396 + if( cidx ) {
1.397 + Node *def = n->in(cidx);
1.398 + if( _phc.Find(n) == _phc.Find(def) ) {
1.399 + n->replace_by(def);
1.400 + n->set_req(cidx,NULL);
1.401 + b->_nodes.remove(l);
1.402 + l--;
1.403 + continue;
1.404 + }
1.405 + }
1.406 +
1.407 + if( n->is_Phi() ) {
1.408 + // Get the chosen name for the Phi
1.409 + uint phi_name = _phc.Find( n );
1.410 + // Ignore the pre-allocated specials
1.411 + if( !phi_name ) continue;
1.412 + // Check for mismatch inputs to Phi
1.413 + for( uint j = 1; j<cnt; j++ ) {
1.414 + Node *m = n->in(j);
1.415 + uint src_name = _phc.Find(m);
1.416 + if( src_name != phi_name ) {
1.417 + Block *pred = _phc._cfg._bbs[b->pred(j)->_idx];
1.418 + Node *copy;
1.419 + assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach");
1.420 + // Rematerialize constants instead of copying them
1.421 + if( m->is_Mach() && m->as_Mach()->is_Con() &&
1.422 + m->as_Mach()->rematerialize() ) {
1.423 + copy = m->clone();
1.424 + // Insert the copy in the predecessor basic block
1.425 + pred->add_inst(copy);
1.426 + // Copy any flags as well
1.427 + _phc.clone_projs( pred, pred->end_idx(), m, copy, _phc._maxlrg );
1.428 + } else {
1.429 + const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()];
1.430 + copy = new (C) MachSpillCopyNode(m,*rm,*rm);
1.431 + // Find a good place to insert. Kinda tricky, use a subroutine
1.432 + insert_copy_with_overlap(pred,copy,phi_name,src_name);
1.433 + }
1.434 + // Insert the copy in the use-def chain
1.435 + n->set_req( j, copy );
1.436 + _phc._cfg._bbs.map( copy->_idx, pred );
1.437 + // Extend ("register allocate") the names array for the copy.
1.438 + _phc._names.extend( copy->_idx, phi_name );
1.439 + } // End of if Phi names do not match
1.440 + } // End of for all inputs to Phi
1.441 + } else { // End of if Phi
1.442 +
1.443 + // Now check for 2-address instructions
1.444 + uint idx;
1.445 + if( n->is_Mach() && (idx=n->as_Mach()->two_adr()) ) {
1.446 + // Get the chosen name for the Node
1.447 + uint name = _phc.Find( n );
1.448 + assert( name, "no 2-address specials" );
1.449 + // Check for name mis-match on the 2-address input
1.450 + Node *m = n->in(idx);
1.451 + if( _phc.Find(m) != name ) {
1.452 + Node *copy;
1.453 + assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach");
1.454 + // At this point it is unsafe to extend live ranges (6550579).
1.455 + // Rematerialize only constants as we do for Phi above.
1.456 + if( m->is_Mach() && m->as_Mach()->is_Con() &&
1.457 + m->as_Mach()->rematerialize() ) {
1.458 + copy = m->clone();
1.459 + // Insert the copy in the basic block, just before us
1.460 + b->_nodes.insert( l++, copy );
1.461 + if( _phc.clone_projs( b, l, m, copy, _phc._maxlrg ) )
1.462 + l++;
1.463 + } else {
1.464 + const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()];
1.465 + copy = new (C) MachSpillCopyNode( m, *rm, *rm );
1.466 + // Insert the copy in the basic block, just before us
1.467 + b->_nodes.insert( l++, copy );
1.468 + }
1.469 + // Insert the copy in the use-def chain
1.470 + n->set_req(idx, copy );
1.471 + // Extend ("register allocate") the names array for the copy.
1.472 + _phc._names.extend( copy->_idx, name );
1.473 + _phc._cfg._bbs.map( copy->_idx, b );
1.474 + }
1.475 +
1.476 + } // End of is two-adr
1.477 +
1.478 + // Insert a copy at a debug use for a lrg which has high frequency
1.479 + if( (b->_freq < OPTO_DEBUG_SPLIT_FREQ) && n->is_MachSafePoint() ) {
1.480 + // Walk the debug inputs to the node and check for lrg freq
1.481 + JVMState* jvms = n->jvms();
1.482 + uint debug_start = jvms ? jvms->debug_start() : 999999;
1.483 + uint debug_end = jvms ? jvms->debug_end() : 999999;
1.484 + for(uint inpidx = debug_start; inpidx < debug_end; inpidx++) {
1.485 + // Do not split monitors; they are only needed for debug table
1.486 + // entries and need no code.
1.487 + if( jvms->is_monitor_use(inpidx) ) continue;
1.488 + Node *inp = n->in(inpidx);
1.489 + uint nidx = _phc.n2lidx(inp);
1.490 + LRG &lrg = lrgs(nidx);
1.491 +
1.492 + // If this lrg has a high frequency use/def
1.493 + if( lrg._maxfreq >= OPTO_LRG_HIGH_FREQ ) {
1.494 + // If the live range is also live out of this block (like it
1.495 + // would be for a fast/slow idiom), the normal spill mechanism
1.496 + // does an excellent job. If it is not live out of this block
1.497 + // (like it would be for debug info to uncommon trap) splitting
1.498 + // the live range now allows a better allocation in the high
1.499 + // frequency blocks.
1.500 + // Build_IFG_virtual has converted the live sets to
1.501 + // live-IN info, not live-OUT info.
1.502 + uint k;
1.503 + for( k=0; k < b->_num_succs; k++ )
1.504 + if( _phc._live->live(b->_succs[k])->member( nidx ) )
1.505 + break; // Live in to some successor block?
1.506 + if( k < b->_num_succs )
1.507 + continue; // Live out; do not pre-split
1.508 + // Split the lrg at this use
1.509 + const RegMask *rm = C->matcher()->idealreg2spillmask[inp->ideal_reg()];
1.510 + Node *copy = new (C) MachSpillCopyNode( inp, *rm, *rm );
1.511 + // Insert the copy in the use-def chain
1.512 + n->set_req(inpidx, copy );
1.513 + // Insert the copy in the basic block, just before us
1.514 + b->_nodes.insert( l++, copy );
1.515 + // Extend ("register allocate") the names array for the copy.
1.516 + _phc.new_lrg( copy, _phc._maxlrg++ );
1.517 + _phc._cfg._bbs.map( copy->_idx, b );
1.518 + //tty->print_cr("Split a debug use in Aggressive Coalesce");
1.519 + } // End of if high frequency use/def
1.520 + } // End of for all debug inputs
1.521 + } // End of if low frequency safepoint
1.522 +
1.523 + } // End of if Phi
1.524 +
1.525 + } // End of for all instructions
1.526 + } // End of for all blocks
1.527 +}
1.528 +
1.529 +//=============================================================================
1.530 +//------------------------------coalesce---------------------------------------
1.531 +// Aggressive (but pessimistic) copy coalescing of a single block
1.532 +
1.533 +// The following coalesce pass represents a single round of aggressive
1.534 +// pessimistic coalesce. "Aggressive" means no attempt to preserve
1.535 +// colorability when coalescing. This occasionally means more spills, but
1.536 +// it also means fewer rounds of coalescing for better code - and that means
1.537 +// faster compiles.
1.538 +
1.539 +// "Pessimistic" means we do not hit the fixed point in one pass (and we are
1.540 +// reaching for the least fixed point to boot). This is typically solved
1.541 +// with a few more rounds of coalescing, but the compiler must run fast. We
1.542 +// could optimistically coalescing everything touching PhiNodes together
1.543 +// into one big live range, then check for self-interference. Everywhere
1.544 +// the live range interferes with self it would have to be split. Finding
1.545 +// the right split points can be done with some heuristics (based on
1.546 +// expected frequency of edges in the live range). In short, it's a real
1.547 +// research problem and the timeline is too short to allow such research.
1.548 +// Further thoughts: (1) build the LR in a pass, (2) find self-interference
1.549 +// in another pass, (3) per each self-conflict, split, (4) split by finding
1.550 +// the low-cost cut (min-cut) of the LR, (5) edges in the LR are weighted
1.551 +// according to the GCM algorithm (or just exec freq on CFG edges).
1.552 +
1.553 +void PhaseAggressiveCoalesce::coalesce( Block *b ) {
1.554 + // Copies are still "virtual" - meaning we have not made them explicitly
1.555 + // copies. Instead, Phi functions of successor blocks have mis-matched
1.556 + // live-ranges. If I fail to coalesce, I'll have to insert a copy to line
1.557 + // up the live-ranges. Check for Phis in successor blocks.
1.558 + uint i;
1.559 + for( i=0; i<b->_num_succs; i++ ) {
1.560 + Block *bs = b->_succs[i];
1.561 + // Find index of 'b' in 'bs' predecessors
1.562 + uint j=1;
1.563 + while( _phc._cfg._bbs[bs->pred(j)->_idx] != b ) j++;
1.564 + // Visit all the Phis in successor block
1.565 + for( uint k = 1; k<bs->_nodes.size(); k++ ) {
1.566 + Node *n = bs->_nodes[k];
1.567 + if( !n->is_Phi() ) break;
1.568 + combine_these_two( n, n->in(j) );
1.569 + }
1.570 + } // End of for all successor blocks
1.571 +
1.572 +
1.573 + // Check _this_ block for 2-address instructions and copies.
1.574 + uint cnt = b->end_idx();
1.575 + for( i = 1; i<cnt; i++ ) {
1.576 + Node *n = b->_nodes[i];
1.577 + uint idx;
1.578 + // 2-address instructions have a virtual Copy matching their input
1.579 + // to their output
1.580 + if( n->is_Mach() && (idx = n->as_Mach()->two_adr()) ) {
1.581 + MachNode *mach = n->as_Mach();
1.582 + combine_these_two( mach, mach->in(idx) );
1.583 + }
1.584 + } // End of for all instructions in block
1.585 +}
1.586 +
1.587 +//=============================================================================
1.588 +//------------------------------PhaseConservativeCoalesce----------------------
1.589 +PhaseConservativeCoalesce::PhaseConservativeCoalesce( PhaseChaitin &chaitin ) : PhaseCoalesce(chaitin) {
1.590 + _ulr.initialize(_phc._maxlrg);
1.591 +}
1.592 +
1.593 +//------------------------------verify-----------------------------------------
1.594 +void PhaseConservativeCoalesce::verify() {
1.595 +#ifdef ASSERT
1.596 + _phc.set_was_low();
1.597 +#endif
1.598 +}
1.599 +
1.600 +//------------------------------union_helper-----------------------------------
1.601 +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 ) {
1.602 + // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the
1.603 + // union-find tree
1.604 + _phc.Union( lr1_node, lr2_node );
1.605 +
1.606 + // Single-def live range ONLY if both live ranges are single-def.
1.607 + // If both are single def, then src_def powers one live range
1.608 + // and def_copy powers the other. After merging, src_def powers
1.609 + // the combined live range.
1.610 + lrgs(lr1)._def = (lrgs(lr1)._def == NodeSentinel ||
1.611 + lrgs(lr2)._def == NodeSentinel )
1.612 + ? NodeSentinel : src_def;
1.613 + lrgs(lr2)._def = NULL; // No def for lrg 2
1.614 + lrgs(lr2).Clear(); // Force empty mask for LRG 2
1.615 + //lrgs(lr2)._size = 0; // Live-range 2 goes dead
1.616 + lrgs(lr1)._is_oop |= lrgs(lr2)._is_oop;
1.617 + lrgs(lr2)._is_oop = 0; // In particular, not an oop for GC info
1.618 +
1.619 + if (lrgs(lr1)._maxfreq < lrgs(lr2)._maxfreq)
1.620 + lrgs(lr1)._maxfreq = lrgs(lr2)._maxfreq;
1.621 +
1.622 + // Copy original value instead. Intermediate copies go dead, and
1.623 + // the dst_copy becomes useless.
1.624 + int didx = dst_copy->is_Copy();
1.625 + dst_copy->set_req( didx, src_def );
1.626 + // Add copy to free list
1.627 + // _phc.free_spillcopy(b->_nodes[bindex]);
1.628 + assert( b->_nodes[bindex] == dst_copy, "" );
1.629 + dst_copy->replace_by( dst_copy->in(didx) );
1.630 + dst_copy->set_req( didx, NULL);
1.631 + b->_nodes.remove(bindex);
1.632 + if( bindex < b->_ihrp_index ) b->_ihrp_index--;
1.633 + if( bindex < b->_fhrp_index ) b->_fhrp_index--;
1.634 +
1.635 + // Stretched lr1; add it to liveness of intermediate blocks
1.636 + Block *b2 = _phc._cfg._bbs[src_copy->_idx];
1.637 + while( b != b2 ) {
1.638 + b = _phc._cfg._bbs[b->pred(1)->_idx];
1.639 + _phc._live->live(b)->insert(lr1);
1.640 + }
1.641 +}
1.642 +
1.643 +//------------------------------compute_separating_interferences---------------
1.644 +// Factored code from copy_copy that computes extra interferences from
1.645 +// lengthening a live range by double-coalescing.
1.646 +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 ) {
1.647 +
1.648 + assert(!lrgs(lr1)._fat_proj, "cannot coalesce fat_proj");
1.649 + assert(!lrgs(lr2)._fat_proj, "cannot coalesce fat_proj");
1.650 + Node *prev_copy = dst_copy->in(dst_copy->is_Copy());
1.651 + Block *b2 = b;
1.652 + uint bindex2 = bindex;
1.653 + while( 1 ) {
1.654 + // Find previous instruction
1.655 + bindex2--; // Chain backwards 1 instruction
1.656 + while( bindex2 == 0 ) { // At block start, find prior block
1.657 + assert( b2->num_preds() == 2, "cannot double coalesce across c-flow" );
1.658 + b2 = _phc._cfg._bbs[b2->pred(1)->_idx];
1.659 + bindex2 = b2->end_idx()-1;
1.660 + }
1.661 + // Get prior instruction
1.662 + assert(bindex2 < b2->_nodes.size(), "index out of bounds");
1.663 + Node *x = b2->_nodes[bindex2];
1.664 + if( x == prev_copy ) { // Previous copy in copy chain?
1.665 + if( prev_copy == src_copy)// Found end of chain and all interferences
1.666 + break; // So break out of loop
1.667 + // Else work back one in copy chain
1.668 + prev_copy = prev_copy->in(prev_copy->is_Copy());
1.669 + } else { // Else collect interferences
1.670 + uint lidx = _phc.Find(x);
1.671 + // Found another def of live-range being stretched?
1.672 + if( lidx == lr1 ) return max_juint;
1.673 + if( lidx == lr2 ) return max_juint;
1.674 +
1.675 + // If we attempt to coalesce across a bound def
1.676 + if( lrgs(lidx).is_bound() ) {
1.677 + // Do not let the coalesced LRG expect to get the bound color
1.678 + rm.SUBTRACT( lrgs(lidx).mask() );
1.679 + // Recompute rm_size
1.680 + rm_size = rm.Size();
1.681 + //if( rm._flags ) rm_size += 1000000;
1.682 + if( reg_degree >= rm_size ) return max_juint;
1.683 + }
1.684 + if( rm.overlap(lrgs(lidx).mask()) ) {
1.685 + // Insert lidx into union LRG; returns TRUE if actually inserted
1.686 + if( _ulr.insert(lidx) ) {
1.687 + // Infinite-stack neighbors do not alter colorability, as they
1.688 + // can always color to some other color.
1.689 + if( !lrgs(lidx).mask().is_AllStack() ) {
1.690 + // If this coalesce will make any new neighbor uncolorable,
1.691 + // do not coalesce.
1.692 + if( lrgs(lidx).just_lo_degree() )
1.693 + return max_juint;
1.694 + // Bump our degree
1.695 + if( ++reg_degree >= rm_size )
1.696 + return max_juint;
1.697 + } // End of if not infinite-stack neighbor
1.698 + } // End of if actually inserted
1.699 + } // End of if live range overlaps
1.700 + } // End of else collect intereferences for 1 node
1.701 + } // End of while forever, scan back for intereferences
1.702 + return reg_degree;
1.703 +}
1.704 +
1.705 +//------------------------------update_ifg-------------------------------------
1.706 +void PhaseConservativeCoalesce::update_ifg(uint lr1, uint lr2, IndexSet *n_lr1, IndexSet *n_lr2) {
1.707 + // Some original neighbors of lr1 might have gone away
1.708 + // because the constrained register mask prevented them.
1.709 + // Remove lr1 from such neighbors.
1.710 + IndexSetIterator one(n_lr1);
1.711 + uint neighbor;
1.712 + LRG &lrg1 = lrgs(lr1);
1.713 + while ((neighbor = one.next()) != 0)
1.714 + if( !_ulr.member(neighbor) )
1.715 + if( _phc._ifg->neighbors(neighbor)->remove(lr1) )
1.716 + lrgs(neighbor).inc_degree( -lrg1.compute_degree(lrgs(neighbor)) );
1.717 +
1.718 +
1.719 + // lr2 is now called (coalesced into) lr1.
1.720 + // Remove lr2 from the IFG.
1.721 + IndexSetIterator two(n_lr2);
1.722 + LRG &lrg2 = lrgs(lr2);
1.723 + while ((neighbor = two.next()) != 0)
1.724 + if( _phc._ifg->neighbors(neighbor)->remove(lr2) )
1.725 + lrgs(neighbor).inc_degree( -lrg2.compute_degree(lrgs(neighbor)) );
1.726 +
1.727 + // Some neighbors of intermediate copies now interfere with the
1.728 + // combined live range.
1.729 + IndexSetIterator three(&_ulr);
1.730 + while ((neighbor = three.next()) != 0)
1.731 + if( _phc._ifg->neighbors(neighbor)->insert(lr1) )
1.732 + lrgs(neighbor).inc_degree( lrg1.compute_degree(lrgs(neighbor)) );
1.733 +}
1.734 +
1.735 +//------------------------------record_bias------------------------------------
1.736 +static void record_bias( const PhaseIFG *ifg, int lr1, int lr2 ) {
1.737 + // Tag copy bias here
1.738 + if( !ifg->lrgs(lr1)._copy_bias )
1.739 + ifg->lrgs(lr1)._copy_bias = lr2;
1.740 + if( !ifg->lrgs(lr2)._copy_bias )
1.741 + ifg->lrgs(lr2)._copy_bias = lr1;
1.742 +}
1.743 +
1.744 +//------------------------------copy_copy--------------------------------------
1.745 +// See if I can coalesce a series of multiple copies together. I need the
1.746 +// final dest copy and the original src copy. They can be the same Node.
1.747 +// Compute the compatible register masks.
1.748 +bool PhaseConservativeCoalesce::copy_copy( Node *dst_copy, Node *src_copy, Block *b, uint bindex ) {
1.749 +
1.750 + if( !dst_copy->is_SpillCopy() ) return false;
1.751 + if( !src_copy->is_SpillCopy() ) return false;
1.752 + Node *src_def = src_copy->in(src_copy->is_Copy());
1.753 + uint lr1 = _phc.Find(dst_copy);
1.754 + uint lr2 = _phc.Find(src_def );
1.755 +
1.756 + // Same live ranges already?
1.757 + if( lr1 == lr2 ) return false;
1.758 +
1.759 + // Interfere?
1.760 + if( _phc._ifg->test_edge_sq( lr1, lr2 ) ) return false;
1.761 +
1.762 + // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK.
1.763 + if( !lrgs(lr1)._is_oop && lrgs(lr2)._is_oop ) // not an oop->int cast
1.764 + return false;
1.765 +
1.766 + // Coalescing between an aligned live range and a mis-aligned live range?
1.767 + // No, no! Alignment changes how we count degree.
1.768 + if( lrgs(lr1)._fat_proj != lrgs(lr2)._fat_proj )
1.769 + return false;
1.770 +
1.771 + // Sort; use smaller live-range number
1.772 + Node *lr1_node = dst_copy;
1.773 + Node *lr2_node = src_def;
1.774 + if( lr1 > lr2 ) {
1.775 + uint tmp = lr1; lr1 = lr2; lr2 = tmp;
1.776 + lr1_node = src_def; lr2_node = dst_copy;
1.777 + }
1.778 +
1.779 + // Check for compatibility of the 2 live ranges by
1.780 + // intersecting their allowed register sets.
1.781 + RegMask rm = lrgs(lr1).mask();
1.782 + rm.AND(lrgs(lr2).mask());
1.783 + // Number of bits free
1.784 + uint rm_size = rm.Size();
1.785 +
1.786 + // If we can use any stack slot, then effective size is infinite
1.787 + if( rm.is_AllStack() ) rm_size += 1000000;
1.788 + // Incompatible masks, no way to coalesce
1.789 + if( rm_size == 0 ) return false;
1.790 +
1.791 + // Another early bail-out test is when we are double-coalescing and the
1.792 + // 2 copies are seperated by some control flow.
1.793 + if( dst_copy != src_copy ) {
1.794 + Block *src_b = _phc._cfg._bbs[src_copy->_idx];
1.795 + Block *b2 = b;
1.796 + while( b2 != src_b ) {
1.797 + if( b2->num_preds() > 2 ){// Found merge-point
1.798 + _phc._lost_opp_cflow_coalesce++;
1.799 + // extra record_bias commented out because Chris believes it is not
1.800 + // productive. Since we can record only 1 bias, we want to choose one
1.801 + // that stands a chance of working and this one probably does not.
1.802 + //record_bias( _phc._lrgs, lr1, lr2 );
1.803 + return false; // To hard to find all interferences
1.804 + }
1.805 + b2 = _phc._cfg._bbs[b2->pred(1)->_idx];
1.806 + }
1.807 + }
1.808 +
1.809 + // Union the two interference sets together into '_ulr'
1.810 + uint reg_degree = _ulr.lrg_union( lr1, lr2, rm_size, _phc._ifg, rm );
1.811 +
1.812 + if( reg_degree >= rm_size ) {
1.813 + record_bias( _phc._ifg, lr1, lr2 );
1.814 + return false;
1.815 + }
1.816 +
1.817 + // Now I need to compute all the interferences between dst_copy and
1.818 + // src_copy. I'm not willing visit the entire interference graph, so
1.819 + // I limit my search to things in dst_copy's block or in a straight
1.820 + // line of previous blocks. I give up at merge points or when I get
1.821 + // more interferences than my degree. I can stop when I find src_copy.
1.822 + if( dst_copy != src_copy ) {
1.823 + reg_degree = compute_separating_interferences(dst_copy, src_copy, b, bindex, rm, rm_size, reg_degree, lr1, lr2 );
1.824 + if( reg_degree == max_juint ) {
1.825 + record_bias( _phc._ifg, lr1, lr2 );
1.826 + return false;
1.827 + }
1.828 + } // End of if dst_copy & src_copy are different
1.829 +
1.830 +
1.831 + // ---- THE COMBINED LRG IS COLORABLE ----
1.832 +
1.833 + // YEAH - Now coalesce this copy away
1.834 + assert( lrgs(lr1).num_regs() == lrgs(lr2).num_regs(), "" );
1.835 +
1.836 + IndexSet *n_lr1 = _phc._ifg->neighbors(lr1);
1.837 + IndexSet *n_lr2 = _phc._ifg->neighbors(lr2);
1.838 +
1.839 + // Update the interference graph
1.840 + update_ifg(lr1, lr2, n_lr1, n_lr2);
1.841 +
1.842 + _ulr.remove(lr1);
1.843 +
1.844 + // Uncomment the following code to trace Coalescing in great detail.
1.845 + //
1.846 + //if (false) {
1.847 + // tty->cr();
1.848 + // tty->print_cr("#######################################");
1.849 + // tty->print_cr("union %d and %d", lr1, lr2);
1.850 + // n_lr1->dump();
1.851 + // n_lr2->dump();
1.852 + // tty->print_cr("resulting set is");
1.853 + // _ulr.dump();
1.854 + //}
1.855 +
1.856 + // Replace n_lr1 with the new combined live range. _ulr will use
1.857 + // n_lr1's old memory on the next iteration. n_lr2 is cleared to
1.858 + // send its internal memory to the free list.
1.859 + _ulr.swap(n_lr1);
1.860 + _ulr.clear();
1.861 + n_lr2->clear();
1.862 +
1.863 + lrgs(lr1).set_degree( _phc._ifg->effective_degree(lr1) );
1.864 + lrgs(lr2).set_degree( 0 );
1.865 +
1.866 + // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the
1.867 + // union-find tree
1.868 + union_helper( lr1_node, lr2_node, lr1, lr2, src_def, dst_copy, src_copy, b, bindex );
1.869 + // Combine register restrictions
1.870 + lrgs(lr1).set_mask(rm);
1.871 + lrgs(lr1).compute_set_mask_size();
1.872 + lrgs(lr1)._cost += lrgs(lr2)._cost;
1.873 + lrgs(lr1)._area += lrgs(lr2)._area;
1.874 +
1.875 + // While its uncommon to successfully coalesce live ranges that started out
1.876 + // being not-lo-degree, it can happen. In any case the combined coalesced
1.877 + // live range better Simplify nicely.
1.878 + lrgs(lr1)._was_lo = 1;
1.879 +
1.880 + // kinda expensive to do all the time
1.881 + //tty->print_cr("warning: slow verify happening");
1.882 + //_phc._ifg->verify( &_phc );
1.883 + return true;
1.884 +}
1.885 +
1.886 +//------------------------------coalesce---------------------------------------
1.887 +// Conservative (but pessimistic) copy coalescing of a single block
1.888 +void PhaseConservativeCoalesce::coalesce( Block *b ) {
1.889 + // Bail out on infrequent blocks
1.890 + if( b->is_uncommon(_phc._cfg._bbs) )
1.891 + return;
1.892 + // Check this block for copies.
1.893 + for( uint i = 1; i<b->end_idx(); i++ ) {
1.894 + // Check for actual copies on inputs. Coalesce a copy into its
1.895 + // input if use and copy's input are compatible.
1.896 + Node *copy1 = b->_nodes[i];
1.897 + uint idx1 = copy1->is_Copy();
1.898 + if( !idx1 ) continue; // Not a copy
1.899 +
1.900 + if( copy_copy(copy1,copy1,b,i) ) {
1.901 + i--; // Retry, same location in block
1.902 + PhaseChaitin::_conserv_coalesce++; // Collect stats on success
1.903 + continue;
1.904 + }
1.905 +
1.906 + /* do not attempt pairs. About 1/2 of all pairs can be removed by
1.907 + post-alloc. The other set are too few to bother.
1.908 + Node *copy2 = copy1->in(idx1);
1.909 + uint idx2 = copy2->is_Copy();
1.910 + if( !idx2 ) continue;
1.911 + if( copy_copy(copy1,copy2,b,i) ) {
1.912 + i--; // Retry, same location in block
1.913 + PhaseChaitin::_conserv_coalesce_pair++; // Collect stats on success
1.914 + continue;
1.915 + }
1.916 + */
1.917 + }
1.918 +}
