| /* |
| * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| * |
| */ |
| |
| #include "incls/_precompiled.incl" |
| #include "incls/_coalesce.cpp.incl" |
| |
| //============================================================================= |
| //------------------------------reset_uf_map----------------------------------- |
| void PhaseChaitin::reset_uf_map( uint maxlrg ) { |
| _maxlrg = maxlrg; |
| // Force the Union-Find mapping to be at least this large |
| _uf_map.extend(_maxlrg,0); |
| // Initialize it to be the ID mapping. |
| for( uint i=0; i<_maxlrg; i++ ) |
| _uf_map.map(i,i); |
| } |
| |
| //------------------------------compress_uf_map-------------------------------- |
| // Make all Nodes map directly to their final live range; no need for |
| // the Union-Find mapping after this call. |
| void PhaseChaitin::compress_uf_map_for_nodes( ) { |
| // For all Nodes, compress mapping |
| uint unique = _names.Size(); |
| for( uint i=0; i<unique; i++ ) { |
| uint lrg = _names[i]; |
| uint compressed_lrg = Find(lrg); |
| if( lrg != compressed_lrg ) |
| _names.map(i,compressed_lrg); |
| } |
| } |
| |
| //------------------------------Find------------------------------------------- |
| // Straight out of Tarjan's union-find algorithm |
| uint PhaseChaitin::Find_compress( uint lrg ) { |
| uint cur = lrg; |
| uint next = _uf_map[cur]; |
| while( next != cur ) { // Scan chain of equivalences |
| assert( next < cur, "always union smaller" ); |
| cur = next; // until find a fixed-point |
| next = _uf_map[cur]; |
| } |
| // Core of union-find algorithm: update chain of |
| // equivalences to be equal to the root. |
| while( lrg != next ) { |
| uint tmp = _uf_map[lrg]; |
| _uf_map.map(lrg, next); |
| lrg = tmp; |
| } |
| return lrg; |
| } |
| |
| //------------------------------Find------------------------------------------- |
| // Straight out of Tarjan's union-find algorithm |
| uint PhaseChaitin::Find_compress( const Node *n ) { |
| uint lrg = Find_compress(_names[n->_idx]); |
| _names.map(n->_idx,lrg); |
| return lrg; |
| } |
| |
| //------------------------------Find_const------------------------------------- |
| // Like Find above, but no path compress, so bad asymptotic behavior |
| uint PhaseChaitin::Find_const( uint lrg ) const { |
| if( !lrg ) return lrg; // Ignore the zero LRG |
| // Off the end? This happens during debugging dumps when you got |
| // brand new live ranges but have not told the allocator yet. |
| if( lrg >= _maxlrg ) return lrg; |
| uint next = _uf_map[lrg]; |
| while( next != lrg ) { // Scan chain of equivalences |
| assert( next < lrg, "always union smaller" ); |
| lrg = next; // until find a fixed-point |
| next = _uf_map[lrg]; |
| } |
| return next; |
| } |
| |
| //------------------------------Find------------------------------------------- |
| // Like Find above, but no path compress, so bad asymptotic behavior |
| uint PhaseChaitin::Find_const( const Node *n ) const { |
| if( n->_idx >= _names.Size() ) return 0; // not mapped, usual for debug dump |
| return Find_const( _names[n->_idx] ); |
| } |
| |
| //------------------------------Union------------------------------------------ |
| // union 2 sets together. |
| void PhaseChaitin::Union( const Node *src_n, const Node *dst_n ) { |
| uint src = Find(src_n); |
| uint dst = Find(dst_n); |
| assert( src, "" ); |
| assert( dst, "" ); |
| assert( src < _maxlrg, "oob" ); |
| assert( dst < _maxlrg, "oob" ); |
| assert( src < dst, "always union smaller" ); |
| _uf_map.map(dst,src); |
| } |
| |
| //------------------------------new_lrg---------------------------------------- |
| void PhaseChaitin::new_lrg( const Node *x, uint lrg ) { |
| // Make the Node->LRG mapping |
| _names.extend(x->_idx,lrg); |
| // Make the Union-Find mapping an identity function |
| _uf_map.extend(lrg,lrg); |
| } |
| |
| //------------------------------clone_projs------------------------------------ |
| // After cloning some rematierialized instruction, clone any MachProj's that |
| // follow it. Example: Intel zero is XOR, kills flags. Sparc FP constants |
| // use G3 as an address temp. |
| int PhaseChaitin::clone_projs( Block *b, uint idx, Node *con, Node *copy, uint &maxlrg ) { |
| Block *bcon = _cfg._bbs[con->_idx]; |
| uint cindex = bcon->find_node(con); |
| Node *con_next = bcon->_nodes[cindex+1]; |
| if( con_next->in(0) != con || con_next->Opcode() != Op_MachProj ) |
| return false; // No MachProj's follow |
| |
| // Copy kills after the cloned constant |
| Node *kills = con_next->clone(); |
| kills->set_req( 0, copy ); |
| b->_nodes.insert( idx, kills ); |
| _cfg._bbs.map( kills->_idx, b ); |
| new_lrg( kills, maxlrg++ ); |
| return true; |
| } |
| |
| //------------------------------compact---------------------------------------- |
| // Renumber the live ranges to compact them. Makes the IFG smaller. |
| void PhaseChaitin::compact() { |
| // Current the _uf_map contains a series of short chains which are headed |
| // by a self-cycle. All the chains run from big numbers to little numbers. |
| // The Find() call chases the chains & shortens them for the next Find call. |
| // We are going to change this structure slightly. Numbers above a moving |
| // wave 'i' are unchanged. Numbers below 'j' point directly to their |
| // compacted live range with no further chaining. There are no chains or |
| // cycles below 'i', so the Find call no longer works. |
| uint j=1; |
| uint i; |
| for( i=1; i < _maxlrg; i++ ) { |
| uint lr = _uf_map[i]; |
| // Ignore unallocated live ranges |
| if( !lr ) continue; |
| assert( lr <= i, "" ); |
| _uf_map.map(i, ( lr == i ) ? j++ : _uf_map[lr]); |
| } |
| if( false ) // PrintOptoCompactLiveRanges |
| printf("Compacted %d LRs from %d\n",i-j,i); |
| // Now change the Node->LR mapping to reflect the compacted names |
| uint unique = _names.Size(); |
| for( i=0; i<unique; i++ ) |
| _names.map(i,_uf_map[_names[i]]); |
| |
| // Reset the Union-Find mapping |
| reset_uf_map(j); |
| |
| } |
| |
| //============================================================================= |
| //------------------------------Dump------------------------------------------- |
| #ifndef PRODUCT |
| void PhaseCoalesce::dump( Node *n ) const { |
| // Being a const function means I cannot use 'Find' |
| uint r = _phc.Find(n); |
| tty->print("L%d/N%d ",r,n->_idx); |
| } |
| |
| //------------------------------dump------------------------------------------- |
| void PhaseCoalesce::dump() const { |
| // I know I have a block layout now, so I can print blocks in a loop |
| for( uint i=0; i<_phc._cfg._num_blocks; i++ ) { |
| uint j; |
| Block *b = _phc._cfg._blocks[i]; |
| // Print a nice block header |
| tty->print("B%d: ",b->_pre_order); |
| for( j=1; j<b->num_preds(); j++ ) |
| tty->print("B%d ", _phc._cfg._bbs[b->pred(j)->_idx]->_pre_order); |
| tty->print("-> "); |
| for( j=0; j<b->_num_succs; j++ ) |
| tty->print("B%d ",b->_succs[j]->_pre_order); |
| tty->print(" IDom: B%d/#%d\n", b->_idom ? b->_idom->_pre_order : 0, b->_dom_depth); |
| uint cnt = b->_nodes.size(); |
| for( j=0; j<cnt; j++ ) { |
| Node *n = b->_nodes[j]; |
| dump( n ); |
| tty->print("\t%s\t",n->Name()); |
| |
| // Dump the inputs |
| uint k; // Exit value of loop |
| for( k=0; k<n->req(); k++ ) // For all required inputs |
| if( n->in(k) ) dump( n->in(k) ); |
| else tty->print("_ "); |
| int any_prec = 0; |
| for( ; k<n->len(); k++ ) // For all precedence inputs |
| if( n->in(k) ) { |
| if( !any_prec++ ) tty->print(" |"); |
| dump( n->in(k) ); |
| } |
| |
| // Dump node-specific info |
| n->dump_spec(tty); |
| tty->print("\n"); |
| |
| } |
| tty->print("\n"); |
| } |
| } |
| #endif |
| |
| //------------------------------combine_these_two------------------------------ |
| // Combine the live ranges def'd by these 2 Nodes. N2 is an input to N1. |
| void PhaseCoalesce::combine_these_two( Node *n1, Node *n2 ) { |
| uint lr1 = _phc.Find(n1); |
| uint lr2 = _phc.Find(n2); |
| if( lr1 != lr2 && // Different live ranges already AND |
| !_phc._ifg->test_edge_sq( lr1, lr2 ) ) { // Do not interfere |
| LRG *lrg1 = &_phc.lrgs(lr1); |
| LRG *lrg2 = &_phc.lrgs(lr2); |
| // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK. |
| |
| // Now, why is int->oop OK? We end up declaring a raw-pointer as an oop |
| // and in general that's a bad thing. However, int->oop conversions only |
| // happen at GC points, so the lifetime of the misclassified raw-pointer |
| // is from the CheckCastPP (that converts it to an oop) backwards up |
| // through a merge point and into the slow-path call, and around the |
| // diamond up to the heap-top check and back down into the slow-path call. |
| // The misclassified raw pointer is NOT live across the slow-path call, |
| // and so does not appear in any GC info, so the fact that it is |
| // misclassified is OK. |
| |
| if( (lrg1->_is_oop || !lrg2->_is_oop) && // not an oop->int cast AND |
| // Compatible final mask |
| lrg1->mask().overlap( lrg2->mask() ) ) { |
| // Merge larger into smaller. |
| if( lr1 > lr2 ) { |
| uint tmp = lr1; lr1 = lr2; lr2 = tmp; |
| Node *n = n1; n1 = n2; n2 = n; |
| LRG *ltmp = lrg1; lrg1 = lrg2; lrg2 = ltmp; |
| } |
| // Union lr2 into lr1 |
| _phc.Union( n1, n2 ); |
| if (lrg1->_maxfreq < lrg2->_maxfreq) |
| lrg1->_maxfreq = lrg2->_maxfreq; |
| // Merge in the IFG |
| _phc._ifg->Union( lr1, lr2 ); |
| // Combine register restrictions |
| lrg1->AND(lrg2->mask()); |
| } |
| } |
| } |
| |
| //------------------------------coalesce_driver-------------------------------- |
| // Copy coalescing |
| void PhaseCoalesce::coalesce_driver( ) { |
| |
| verify(); |
| // Coalesce from high frequency to low |
| for( uint i=0; i<_phc._cfg._num_blocks; i++ ) |
| coalesce( _phc._blks[i] ); |
| |
| } |
| |
| //------------------------------insert_copy_with_overlap----------------------- |
| // I am inserting copies to come out of SSA form. In the general case, I am |
| // doing a parallel renaming. I'm in the Named world now, so I can't do a |
| // general parallel renaming. All the copies now use "names" (live-ranges) |
| // to carry values instead of the explicit use-def chains. Suppose I need to |
| // insert 2 copies into the same block. They copy L161->L128 and L128->L132. |
| // If I insert them in the wrong order then L128 will get clobbered before it |
| // can get used by the second copy. This cannot happen in the SSA model; |
| // direct use-def chains get me the right value. It DOES happen in the named |
| // model so I have to handle the reordering of copies. |
| // |
| // In general, I need to topo-sort the placed copies to avoid conflicts. |
| // Its possible to have a closed cycle of copies (e.g., recirculating the same |
| // values around a loop). In this case I need a temp to break the cycle. |
| void PhaseAggressiveCoalesce::insert_copy_with_overlap( Block *b, Node *copy, uint dst_name, uint src_name ) { |
| |
| // Scan backwards for the locations of the last use of the dst_name. |
| // I am about to clobber the dst_name, so the copy must be inserted |
| // after the last use. Last use is really first-use on a backwards scan. |
| uint i = b->end_idx()-1; |
| while( 1 ) { |
| Node *n = b->_nodes[i]; |
| // Check for end of virtual copies; this is also the end of the |
| // parallel renaming effort. |
| if( n->_idx < _unique ) break; |
| uint idx = n->is_Copy(); |
| assert( idx || n->is_Con() || n->Opcode() == Op_MachProj, "Only copies during parallel renaming" ); |
| if( idx && _phc.Find(n->in(idx)) == dst_name ) break; |
| i--; |
| } |
| uint last_use_idx = i; |
| |
| // Also search for any kill of src_name that exits the block. |
| // Since the copy uses src_name, I have to come before any kill. |
| uint kill_src_idx = b->end_idx(); |
| // There can be only 1 kill that exits any block and that is |
| // the last kill. Thus it is the first kill on a backwards scan. |
| i = b->end_idx()-1; |
| while( 1 ) { |
| Node *n = b->_nodes[i]; |
| // Check for end of virtual copies; this is also the end of the |
| // parallel renaming effort. |
| if( n->_idx < _unique ) break; |
| assert( n->is_Copy() || n->is_Con() || n->Opcode() == Op_MachProj, "Only copies during parallel renaming" ); |
| if( _phc.Find(n) == src_name ) { |
| kill_src_idx = i; |
| break; |
| } |
| i--; |
| } |
| // Need a temp? Last use of dst comes after the kill of src? |
| if( last_use_idx >= kill_src_idx ) { |
| // Need to break a cycle with a temp |
| uint idx = copy->is_Copy(); |
| Node *tmp = copy->clone(); |
| _phc.new_lrg(tmp,_phc._maxlrg++); |
| // Insert new temp between copy and source |
| tmp ->set_req(idx,copy->in(idx)); |
| copy->set_req(idx,tmp); |
| // Save source in temp early, before source is killed |
| b->_nodes.insert(kill_src_idx,tmp); |
| _phc._cfg._bbs.map( tmp->_idx, b ); |
| last_use_idx++; |
| } |
| |
| // Insert just after last use |
| b->_nodes.insert(last_use_idx+1,copy); |
| } |
| |
| //------------------------------insert_copies---------------------------------- |
| void PhaseAggressiveCoalesce::insert_copies( Matcher &matcher ) { |
| // We do LRGs compressing and fix a liveout data only here since the other |
| // place in Split() is guarded by the assert which we never hit. |
| _phc.compress_uf_map_for_nodes(); |
| // Fix block's liveout data for compressed live ranges. |
| for(uint lrg = 1; lrg < _phc._maxlrg; lrg++ ) { |
| uint compressed_lrg = _phc.Find(lrg); |
| if( lrg != compressed_lrg ) { |
| for( uint bidx = 0; bidx < _phc._cfg._num_blocks; bidx++ ) { |
| IndexSet *liveout = _phc._live->live(_phc._cfg._blocks[bidx]); |
| if( liveout->member(lrg) ) { |
| liveout->remove(lrg); |
| liveout->insert(compressed_lrg); |
| } |
| } |
| } |
| } |
| |
| // All new nodes added are actual copies to replace virtual copies. |
| // Nodes with index less than '_unique' are original, non-virtual Nodes. |
| _unique = C->unique(); |
| |
| for( uint i=0; i<_phc._cfg._num_blocks; i++ ) { |
| Block *b = _phc._cfg._blocks[i]; |
| uint cnt = b->num_preds(); // Number of inputs to the Phi |
| |
| for( uint l = 1; l<b->_nodes.size(); l++ ) { |
| Node *n = b->_nodes[l]; |
| |
| // Do not use removed-copies, use copied value instead |
| uint ncnt = n->req(); |
| for( uint k = 1; k<ncnt; k++ ) { |
| Node *copy = n->in(k); |
| uint cidx = copy->is_Copy(); |
| if( cidx ) { |
| Node *def = copy->in(cidx); |
| if( _phc.Find(copy) == _phc.Find(def) ) |
| n->set_req(k,def); |
| } |
| } |
| |
| // Remove any explicit copies that get coalesced. |
| uint cidx = n->is_Copy(); |
| if( cidx ) { |
| Node *def = n->in(cidx); |
| if( _phc.Find(n) == _phc.Find(def) ) { |
| n->replace_by(def); |
| n->set_req(cidx,NULL); |
| b->_nodes.remove(l); |
| l--; |
| continue; |
| } |
| } |
| |
| if( n->is_Phi() ) { |
| // Get the chosen name for the Phi |
| uint phi_name = _phc.Find( n ); |
| // Ignore the pre-allocated specials |
| if( !phi_name ) continue; |
| // Check for mismatch inputs to Phi |
| for( uint j = 1; j<cnt; j++ ) { |
| Node *m = n->in(j); |
| uint src_name = _phc.Find(m); |
| if( src_name != phi_name ) { |
| Block *pred = _phc._cfg._bbs[b->pred(j)->_idx]; |
| Node *copy; |
| assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach"); |
| // Rematerialize constants instead of copying them |
| if( m->is_Mach() && m->as_Mach()->is_Con() && |
| m->as_Mach()->rematerialize() ) { |
| copy = m->clone(); |
| // Insert the copy in the predecessor basic block |
| pred->add_inst(copy); |
| // Copy any flags as well |
| _phc.clone_projs( pred, pred->end_idx(), m, copy, _phc._maxlrg ); |
| } else { |
| const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()]; |
| copy = new (C) MachSpillCopyNode(m,*rm,*rm); |
| // Find a good place to insert. Kinda tricky, use a subroutine |
| insert_copy_with_overlap(pred,copy,phi_name,src_name); |
| } |
| // Insert the copy in the use-def chain |
| n->set_req( j, copy ); |
| _phc._cfg._bbs.map( copy->_idx, pred ); |
| // Extend ("register allocate") the names array for the copy. |
| _phc._names.extend( copy->_idx, phi_name ); |
| } // End of if Phi names do not match |
| } // End of for all inputs to Phi |
| } else { // End of if Phi |
| |
| // Now check for 2-address instructions |
| uint idx; |
| if( n->is_Mach() && (idx=n->as_Mach()->two_adr()) ) { |
| // Get the chosen name for the Node |
| uint name = _phc.Find( n ); |
| assert( name, "no 2-address specials" ); |
| // Check for name mis-match on the 2-address input |
| Node *m = n->in(idx); |
| if( _phc.Find(m) != name ) { |
| Node *copy; |
| assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach"); |
| // At this point it is unsafe to extend live ranges (6550579). |
| // Rematerialize only constants as we do for Phi above. |
| if( m->is_Mach() && m->as_Mach()->is_Con() && |
| m->as_Mach()->rematerialize() ) { |
| copy = m->clone(); |
| // Insert the copy in the basic block, just before us |
| b->_nodes.insert( l++, copy ); |
| if( _phc.clone_projs( b, l, m, copy, _phc._maxlrg ) ) |
| l++; |
| } else { |
| const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()]; |
| copy = new (C) MachSpillCopyNode( m, *rm, *rm ); |
| // Insert the copy in the basic block, just before us |
| b->_nodes.insert( l++, copy ); |
| } |
| // Insert the copy in the use-def chain |
| n->set_req(idx, copy ); |
| // Extend ("register allocate") the names array for the copy. |
| _phc._names.extend( copy->_idx, name ); |
| _phc._cfg._bbs.map( copy->_idx, b ); |
| } |
| |
| } // End of is two-adr |
| |
| // Insert a copy at a debug use for a lrg which has high frequency |
| if( (b->_freq < OPTO_DEBUG_SPLIT_FREQ) && n->is_MachSafePoint() ) { |
| // Walk the debug inputs to the node and check for lrg freq |
| JVMState* jvms = n->jvms(); |
| uint debug_start = jvms ? jvms->debug_start() : 999999; |
| uint debug_end = jvms ? jvms->debug_end() : 999999; |
| for(uint inpidx = debug_start; inpidx < debug_end; inpidx++) { |
| // Do not split monitors; they are only needed for debug table |
| // entries and need no code. |
| if( jvms->is_monitor_use(inpidx) ) continue; |
| Node *inp = n->in(inpidx); |
| uint nidx = _phc.n2lidx(inp); |
| LRG &lrg = lrgs(nidx); |
| |
| // If this lrg has a high frequency use/def |
| if( lrg._maxfreq >= OPTO_LRG_HIGH_FREQ ) { |
| // If the live range is also live out of this block (like it |
| // would be for a fast/slow idiom), the normal spill mechanism |
| // does an excellent job. If it is not live out of this block |
| // (like it would be for debug info to uncommon trap) splitting |
| // the live range now allows a better allocation in the high |
| // frequency blocks. |
| // Build_IFG_virtual has converted the live sets to |
| // live-IN info, not live-OUT info. |
| uint k; |
| for( k=0; k < b->_num_succs; k++ ) |
| if( _phc._live->live(b->_succs[k])->member( nidx ) ) |
| break; // Live in to some successor block? |
| if( k < b->_num_succs ) |
| continue; // Live out; do not pre-split |
| // Split the lrg at this use |
| const RegMask *rm = C->matcher()->idealreg2spillmask[inp->ideal_reg()]; |
| Node *copy = new (C) MachSpillCopyNode( inp, *rm, *rm ); |
| // Insert the copy in the use-def chain |
| n->set_req(inpidx, copy ); |
| // Insert the copy in the basic block, just before us |
| b->_nodes.insert( l++, copy ); |
| // Extend ("register allocate") the names array for the copy. |
| _phc.new_lrg( copy, _phc._maxlrg++ ); |
| _phc._cfg._bbs.map( copy->_idx, b ); |
| //tty->print_cr("Split a debug use in Aggressive Coalesce"); |
| } // End of if high frequency use/def |
| } // End of for all debug inputs |
| } // End of if low frequency safepoint |
| |
| } // End of if Phi |
| |
| } // End of for all instructions |
| } // End of for all blocks |
| } |
| |
| //============================================================================= |
| //------------------------------coalesce--------------------------------------- |
| // Aggressive (but pessimistic) copy coalescing of a single block |
| |
| // The following coalesce pass represents a single round of aggressive |
| // pessimistic coalesce. "Aggressive" means no attempt to preserve |
| // colorability when coalescing. This occasionally means more spills, but |
| // it also means fewer rounds of coalescing for better code - and that means |
| // faster compiles. |
| |
| // "Pessimistic" means we do not hit the fixed point in one pass (and we are |
| // reaching for the least fixed point to boot). This is typically solved |
| // with a few more rounds of coalescing, but the compiler must run fast. We |
| // could optimistically coalescing everything touching PhiNodes together |
| // into one big live range, then check for self-interference. Everywhere |
| // the live range interferes with self it would have to be split. Finding |
| // the right split points can be done with some heuristics (based on |
| // expected frequency of edges in the live range). In short, it's a real |
| // research problem and the timeline is too short to allow such research. |
| // Further thoughts: (1) build the LR in a pass, (2) find self-interference |
| // in another pass, (3) per each self-conflict, split, (4) split by finding |
| // the low-cost cut (min-cut) of the LR, (5) edges in the LR are weighted |
| // according to the GCM algorithm (or just exec freq on CFG edges). |
| |
| void PhaseAggressiveCoalesce::coalesce( Block *b ) { |
| // Copies are still "virtual" - meaning we have not made them explicitly |
| // copies. Instead, Phi functions of successor blocks have mis-matched |
| // live-ranges. If I fail to coalesce, I'll have to insert a copy to line |
| // up the live-ranges. Check for Phis in successor blocks. |
| uint i; |
| for( i=0; i<b->_num_succs; i++ ) { |
| Block *bs = b->_succs[i]; |
| // Find index of 'b' in 'bs' predecessors |
| uint j=1; |
| while( _phc._cfg._bbs[bs->pred(j)->_idx] != b ) j++; |
| // Visit all the Phis in successor block |
| for( uint k = 1; k<bs->_nodes.size(); k++ ) { |
| Node *n = bs->_nodes[k]; |
| if( !n->is_Phi() ) break; |
| combine_these_two( n, n->in(j) ); |
| } |
| } // End of for all successor blocks |
| |
| |
| // Check _this_ block for 2-address instructions and copies. |
| uint cnt = b->end_idx(); |
| for( i = 1; i<cnt; i++ ) { |
| Node *n = b->_nodes[i]; |
| uint idx; |
| // 2-address instructions have a virtual Copy matching their input |
| // to their output |
| if( n->is_Mach() && (idx = n->as_Mach()->two_adr()) ) { |
| MachNode *mach = n->as_Mach(); |
| combine_these_two( mach, mach->in(idx) ); |
| } |
| } // End of for all instructions in block |
| } |
| |
| //============================================================================= |
| //------------------------------PhaseConservativeCoalesce---------------------- |
| PhaseConservativeCoalesce::PhaseConservativeCoalesce( PhaseChaitin &chaitin ) : PhaseCoalesce(chaitin) { |
| _ulr.initialize(_phc._maxlrg); |
| } |
| |
| //------------------------------verify----------------------------------------- |
| void PhaseConservativeCoalesce::verify() { |
| #ifdef ASSERT |
| _phc.set_was_low(); |
| #endif |
| } |
| |
| //------------------------------union_helper----------------------------------- |
| 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 ) { |
| // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the |
| // union-find tree |
| _phc.Union( lr1_node, lr2_node ); |
| |
| // Single-def live range ONLY if both live ranges are single-def. |
| // If both are single def, then src_def powers one live range |
| // and def_copy powers the other. After merging, src_def powers |
| // the combined live range. |
| lrgs(lr1)._def = (lrgs(lr1).is_multidef() || |
| lrgs(lr2).is_multidef() ) |
| ? NodeSentinel : src_def; |
| lrgs(lr2)._def = NULL; // No def for lrg 2 |
| lrgs(lr2).Clear(); // Force empty mask for LRG 2 |
| //lrgs(lr2)._size = 0; // Live-range 2 goes dead |
| lrgs(lr1)._is_oop |= lrgs(lr2)._is_oop; |
| lrgs(lr2)._is_oop = 0; // In particular, not an oop for GC info |
| |
| if (lrgs(lr1)._maxfreq < lrgs(lr2)._maxfreq) |
| lrgs(lr1)._maxfreq = lrgs(lr2)._maxfreq; |
| |
| // Copy original value instead. Intermediate copies go dead, and |
| // the dst_copy becomes useless. |
| int didx = dst_copy->is_Copy(); |
| dst_copy->set_req( didx, src_def ); |
| // Add copy to free list |
| // _phc.free_spillcopy(b->_nodes[bindex]); |
| assert( b->_nodes[bindex] == dst_copy, "" ); |
| dst_copy->replace_by( dst_copy->in(didx) ); |
| dst_copy->set_req( didx, NULL); |
| b->_nodes.remove(bindex); |
| if( bindex < b->_ihrp_index ) b->_ihrp_index--; |
| if( bindex < b->_fhrp_index ) b->_fhrp_index--; |
| |
| // Stretched lr1; add it to liveness of intermediate blocks |
| Block *b2 = _phc._cfg._bbs[src_copy->_idx]; |
| while( b != b2 ) { |
| b = _phc._cfg._bbs[b->pred(1)->_idx]; |
| _phc._live->live(b)->insert(lr1); |
| } |
| } |
| |
| //------------------------------compute_separating_interferences--------------- |
| // Factored code from copy_copy that computes extra interferences from |
| // lengthening a live range by double-coalescing. |
| 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 ) { |
| |
| assert(!lrgs(lr1)._fat_proj, "cannot coalesce fat_proj"); |
| assert(!lrgs(lr2)._fat_proj, "cannot coalesce fat_proj"); |
| Node *prev_copy = dst_copy->in(dst_copy->is_Copy()); |
| Block *b2 = b; |
| uint bindex2 = bindex; |
| while( 1 ) { |
| // Find previous instruction |
| bindex2--; // Chain backwards 1 instruction |
| while( bindex2 == 0 ) { // At block start, find prior block |
| assert( b2->num_preds() == 2, "cannot double coalesce across c-flow" ); |
| b2 = _phc._cfg._bbs[b2->pred(1)->_idx]; |
| bindex2 = b2->end_idx()-1; |
| } |
| // Get prior instruction |
| assert(bindex2 < b2->_nodes.size(), "index out of bounds"); |
| Node *x = b2->_nodes[bindex2]; |
| if( x == prev_copy ) { // Previous copy in copy chain? |
| if( prev_copy == src_copy)// Found end of chain and all interferences |
| break; // So break out of loop |
| // Else work back one in copy chain |
| prev_copy = prev_copy->in(prev_copy->is_Copy()); |
| } else { // Else collect interferences |
| uint lidx = _phc.Find(x); |
| // Found another def of live-range being stretched? |
| if( lidx == lr1 ) return max_juint; |
| if( lidx == lr2 ) return max_juint; |
| |
| // If we attempt to coalesce across a bound def |
| if( lrgs(lidx).is_bound() ) { |
| // Do not let the coalesced LRG expect to get the bound color |
| rm.SUBTRACT( lrgs(lidx).mask() ); |
| // Recompute rm_size |
| rm_size = rm.Size(); |
| //if( rm._flags ) rm_size += 1000000; |
| if( reg_degree >= rm_size ) return max_juint; |
| } |
| if( rm.overlap(lrgs(lidx).mask()) ) { |
| // Insert lidx into union LRG; returns TRUE if actually inserted |
| if( _ulr.insert(lidx) ) { |
| // Infinite-stack neighbors do not alter colorability, as they |
| // can always color to some other color. |
| if( !lrgs(lidx).mask().is_AllStack() ) { |
| // If this coalesce will make any new neighbor uncolorable, |
| // do not coalesce. |
| if( lrgs(lidx).just_lo_degree() ) |
| return max_juint; |
| // Bump our degree |
| if( ++reg_degree >= rm_size ) |
| return max_juint; |
| } // End of if not infinite-stack neighbor |
| } // End of if actually inserted |
| } // End of if live range overlaps |
| } // End of else collect intereferences for 1 node |
| } // End of while forever, scan back for intereferences |
| return reg_degree; |
| } |
| |
| //------------------------------update_ifg------------------------------------- |
| void PhaseConservativeCoalesce::update_ifg(uint lr1, uint lr2, IndexSet *n_lr1, IndexSet *n_lr2) { |
| // Some original neighbors of lr1 might have gone away |
| // because the constrained register mask prevented them. |
| // Remove lr1 from such neighbors. |
| IndexSetIterator one(n_lr1); |
| uint neighbor; |
| LRG &lrg1 = lrgs(lr1); |
| while ((neighbor = one.next()) != 0) |
| if( !_ulr.member(neighbor) ) |
| if( _phc._ifg->neighbors(neighbor)->remove(lr1) ) |
| lrgs(neighbor).inc_degree( -lrg1.compute_degree(lrgs(neighbor)) ); |
| |
| |
| // lr2 is now called (coalesced into) lr1. |
| // Remove lr2 from the IFG. |
| IndexSetIterator two(n_lr2); |
| LRG &lrg2 = lrgs(lr2); |
| while ((neighbor = two.next()) != 0) |
| if( _phc._ifg->neighbors(neighbor)->remove(lr2) ) |
| lrgs(neighbor).inc_degree( -lrg2.compute_degree(lrgs(neighbor)) ); |
| |
| // Some neighbors of intermediate copies now interfere with the |
| // combined live range. |
| IndexSetIterator three(&_ulr); |
| while ((neighbor = three.next()) != 0) |
| if( _phc._ifg->neighbors(neighbor)->insert(lr1) ) |
| lrgs(neighbor).inc_degree( lrg1.compute_degree(lrgs(neighbor)) ); |
| } |
| |
| //------------------------------record_bias------------------------------------ |
| static void record_bias( const PhaseIFG *ifg, int lr1, int lr2 ) { |
| // Tag copy bias here |
| if( !ifg->lrgs(lr1)._copy_bias ) |
| ifg->lrgs(lr1)._copy_bias = lr2; |
| if( !ifg->lrgs(lr2)._copy_bias ) |
| ifg->lrgs(lr2)._copy_bias = lr1; |
| } |
| |
| //------------------------------copy_copy-------------------------------------- |
| // See if I can coalesce a series of multiple copies together. I need the |
| // final dest copy and the original src copy. They can be the same Node. |
| // Compute the compatible register masks. |
| bool PhaseConservativeCoalesce::copy_copy( Node *dst_copy, Node *src_copy, Block *b, uint bindex ) { |
| |
| if( !dst_copy->is_SpillCopy() ) return false; |
| if( !src_copy->is_SpillCopy() ) return false; |
| Node *src_def = src_copy->in(src_copy->is_Copy()); |
| uint lr1 = _phc.Find(dst_copy); |
| uint lr2 = _phc.Find(src_def ); |
| |
| // Same live ranges already? |
| if( lr1 == lr2 ) return false; |
| |
| // Interfere? |
| if( _phc._ifg->test_edge_sq( lr1, lr2 ) ) return false; |
| |
| // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK. |
| if( !lrgs(lr1)._is_oop && lrgs(lr2)._is_oop ) // not an oop->int cast |
| return false; |
| |
| // Coalescing between an aligned live range and a mis-aligned live range? |
| // No, no! Alignment changes how we count degree. |
| if( lrgs(lr1)._fat_proj != lrgs(lr2)._fat_proj ) |
| return false; |
| |
| // Sort; use smaller live-range number |
| Node *lr1_node = dst_copy; |
| Node *lr2_node = src_def; |
| if( lr1 > lr2 ) { |
| uint tmp = lr1; lr1 = lr2; lr2 = tmp; |
| lr1_node = src_def; lr2_node = dst_copy; |
| } |
| |
| // Check for compatibility of the 2 live ranges by |
| // intersecting their allowed register sets. |
| RegMask rm = lrgs(lr1).mask(); |
| rm.AND(lrgs(lr2).mask()); |
| // Number of bits free |
| uint rm_size = rm.Size(); |
| |
| // If we can use any stack slot, then effective size is infinite |
| if( rm.is_AllStack() ) rm_size += 1000000; |
| // Incompatible masks, no way to coalesce |
| if( rm_size == 0 ) return false; |
| |
| // Another early bail-out test is when we are double-coalescing and the |
| // 2 copies are seperated by some control flow. |
| if( dst_copy != src_copy ) { |
| Block *src_b = _phc._cfg._bbs[src_copy->_idx]; |
| Block *b2 = b; |
| while( b2 != src_b ) { |
| if( b2->num_preds() > 2 ){// Found merge-point |
| _phc._lost_opp_cflow_coalesce++; |
| // extra record_bias commented out because Chris believes it is not |
| // productive. Since we can record only 1 bias, we want to choose one |
| // that stands a chance of working and this one probably does not. |
| //record_bias( _phc._lrgs, lr1, lr2 ); |
| return false; // To hard to find all interferences |
| } |
| b2 = _phc._cfg._bbs[b2->pred(1)->_idx]; |
| } |
| } |
| |
| // Union the two interference sets together into '_ulr' |
| uint reg_degree = _ulr.lrg_union( lr1, lr2, rm_size, _phc._ifg, rm ); |
| |
| if( reg_degree >= rm_size ) { |
| record_bias( _phc._ifg, lr1, lr2 ); |
| return false; |
| } |
| |
| // Now I need to compute all the interferences between dst_copy and |
| // src_copy. I'm not willing visit the entire interference graph, so |
| // I limit my search to things in dst_copy's block or in a straight |
| // line of previous blocks. I give up at merge points or when I get |
| // more interferences than my degree. I can stop when I find src_copy. |
| if( dst_copy != src_copy ) { |
| reg_degree = compute_separating_interferences(dst_copy, src_copy, b, bindex, rm, rm_size, reg_degree, lr1, lr2 ); |
| if( reg_degree == max_juint ) { |
| record_bias( _phc._ifg, lr1, lr2 ); |
| return false; |
| } |
| } // End of if dst_copy & src_copy are different |
| |
| |
| // ---- THE COMBINED LRG IS COLORABLE ---- |
| |
| // YEAH - Now coalesce this copy away |
| assert( lrgs(lr1).num_regs() == lrgs(lr2).num_regs(), "" ); |
| |
| IndexSet *n_lr1 = _phc._ifg->neighbors(lr1); |
| IndexSet *n_lr2 = _phc._ifg->neighbors(lr2); |
| |
| // Update the interference graph |
| update_ifg(lr1, lr2, n_lr1, n_lr2); |
| |
| _ulr.remove(lr1); |
| |
| // Uncomment the following code to trace Coalescing in great detail. |
| // |
| //if (false) { |
| // tty->cr(); |
| // tty->print_cr("#######################################"); |
| // tty->print_cr("union %d and %d", lr1, lr2); |
| // n_lr1->dump(); |
| // n_lr2->dump(); |
| // tty->print_cr("resulting set is"); |
| // _ulr.dump(); |
| //} |
| |
| // Replace n_lr1 with the new combined live range. _ulr will use |
| // n_lr1's old memory on the next iteration. n_lr2 is cleared to |
| // send its internal memory to the free list. |
| _ulr.swap(n_lr1); |
| _ulr.clear(); |
| n_lr2->clear(); |
| |
| lrgs(lr1).set_degree( _phc._ifg->effective_degree(lr1) ); |
| lrgs(lr2).set_degree( 0 ); |
| |
| // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the |
| // union-find tree |
| union_helper( lr1_node, lr2_node, lr1, lr2, src_def, dst_copy, src_copy, b, bindex ); |
| // Combine register restrictions |
| lrgs(lr1).set_mask(rm); |
| lrgs(lr1).compute_set_mask_size(); |
| lrgs(lr1)._cost += lrgs(lr2)._cost; |
| lrgs(lr1)._area += lrgs(lr2)._area; |
| |
| // While its uncommon to successfully coalesce live ranges that started out |
| // being not-lo-degree, it can happen. In any case the combined coalesced |
| // live range better Simplify nicely. |
| lrgs(lr1)._was_lo = 1; |
| |
| // kinda expensive to do all the time |
| //tty->print_cr("warning: slow verify happening"); |
| //_phc._ifg->verify( &_phc ); |
| return true; |
| } |
| |
| //------------------------------coalesce--------------------------------------- |
| // Conservative (but pessimistic) copy coalescing of a single block |
| void PhaseConservativeCoalesce::coalesce( Block *b ) { |
| // Bail out on infrequent blocks |
| if( b->is_uncommon(_phc._cfg._bbs) ) |
| return; |
| // Check this block for copies. |
| for( uint i = 1; i<b->end_idx(); i++ ) { |
| // Check for actual copies on inputs. Coalesce a copy into its |
| // input if use and copy's input are compatible. |
| Node *copy1 = b->_nodes[i]; |
| uint idx1 = copy1->is_Copy(); |
| if( !idx1 ) continue; // Not a copy |
| |
| if( copy_copy(copy1,copy1,b,i) ) { |
| i--; // Retry, same location in block |
| PhaseChaitin::_conserv_coalesce++; // Collect stats on success |
| continue; |
| } |
| |
| /* do not attempt pairs. About 1/2 of all pairs can be removed by |
| post-alloc. The other set are too few to bother. |
| Node *copy2 = copy1->in(idx1); |
| uint idx2 = copy2->is_Copy(); |
| if( !idx2 ) continue; |
| if( copy_copy(copy1,copy2,b,i) ) { |
| i--; // Retry, same location in block |
| PhaseChaitin::_conserv_coalesce_pair++; // Collect stats on success |
| continue; |
| } |
| */ |
| } |
| } |
