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 /*

  * Copyright (c) 2000, 2012, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "compiler/compileLog.hpp"

 #include "compiler/oopMap.hpp"

 #include "memory/allocation.inline.hpp"

 #include "opto/addnode.hpp"

 #include "opto/block.hpp"

 #include "opto/callnode.hpp"

 #include "opto/cfgnode.hpp"

 #include "opto/chaitin.hpp"

 #include "opto/coalesce.hpp"

 #include "opto/connode.hpp"

 #include "opto/idealGraphPrinter.hpp"

 #include "opto/indexSet.hpp"

 #include "opto/machnode.hpp"

 #include "opto/memnode.hpp"

 #include "opto/opcodes.hpp"

 #include "opto/rootnode.hpp"

 //=============================================================================

 #ifndef PRODUCT

 void LRG::dump( ) const {

   ttyLocker ttyl;

   tty->print("%d ",num_regs());

   _mask.dump();

   if( _msize_valid ) {

     if( mask_size() == compute_mask_size() ) tty->print(", #%d ",_mask_size);

     else tty->print(", #!!!_%d_vs_%d ",_mask_size,_mask.Size());

   } else {

     tty->print(", #?(%d) ",_mask.Size());

   }

   tty->print("EffDeg: ");

   if( _degree_valid ) tty->print( "%d ", _eff_degree );

   else tty->print("? ");

   if( is_multidef() ) {

     tty->print("MultiDef ");

     if (_defs != NULL) {

       tty->print("(");

       for (int i = 0; i < _defs->length(); i++) {

         tty->print("N%d ", _defs->at(i)->_idx);

       }

       tty->print(") ");

     }

   }

   else if( _def == 0 ) tty->print("Dead ");

   else tty->print("Def: N%d ",_def->_idx);

   tty->print("Cost:%4.2g Area:%4.2g Score:%4.2g ",_cost,_area, score());

   // Flags

   if( _is_oop ) tty->print("Oop ");

   if( _is_float ) tty->print("Float ");

   if( _is_vector ) tty->print("Vector ");

   if( _was_spilled1 ) tty->print("Spilled ");

   if( _was_spilled2 ) tty->print("Spilled2 ");

   if( _direct_conflict ) tty->print("Direct_conflict ");

   if( _fat_proj ) tty->print("Fat ");

   if( _was_lo ) tty->print("Lo ");

   if( _has_copy ) tty->print("Copy ");

   if( _at_risk ) tty->print("Risk ");

   if( _must_spill ) tty->print("Must_spill ");

   if( _is_bound ) tty->print("Bound ");

   if( _msize_valid ) {

     if( _degree_valid && lo_degree() ) tty->print("Trivial ");

   }

   tty->cr();

 }

 #endif

 //------------------------------score------------------------------------------

 // Compute score from cost and area.  Low score is best to spill.

 static double raw_score( double cost, double area ) {

   return cost - (area*RegisterCostAreaRatio) * 1.52588e-5;

 }

 double LRG::score() const {

   // Scale _area by RegisterCostAreaRatio/64K then subtract from cost.

   // Bigger area lowers score, encourages spilling this live range.

   // Bigger cost raise score, prevents spilling this live range.

   // (Note: 1/65536 is the magic constant below; I dont trust the C optimizer

   // to turn a divide by a constant into a multiply by the reciprical).

   double score = raw_score( _cost, _area);

   // Account for area.  Basically, LRGs covering large areas are better

   // to spill because more other LRGs get freed up.

   if( _area == 0.0 )            // No area?  Then no progress to spill

     return 1e35;

   if( _was_spilled2 )           // If spilled once before, we are unlikely

     return score + 1e30;        // to make progress again.

   if( _cost >= _area*3.0 )      // Tiny area relative to cost

     return score + 1e17;        // Probably no progress to spill

   if( (_cost+_cost) >= _area*3.0 ) // Small area relative to cost

     return score + 1e10;        // Likely no progress to spill

   return score;

 }

 //------------------------------LRG_List---------------------------------------

 LRG_List::LRG_List( uint max ) : _cnt(max), _max(max), _lidxs(NEW_RESOURCE_ARRAY(uint,max)) {

   memset( _lidxs, 0, sizeof(uint)*max );

 }

 void LRG_List::extend( uint nidx, uint lidx ) {

   _nesting.check();

   if( nidx >= _max ) {

     uint size = 16;

     while( size <= nidx ) size <<=1;

     _lidxs = REALLOC_RESOURCE_ARRAY( uint, _lidxs, _max, size );

     _max = size;

   }

   while( _cnt <= nidx )

     _lidxs[_cnt++] = 0;

   _lidxs[nidx] = lidx;

 }

 #define NUMBUCKS 3

 // Straight out of Tarjan's union-find algorithm

 uint LiveRangeMap::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;

 }

 // Reset the Union-Find map to identity

 void LiveRangeMap::reset_uf_map(uint max_lrg_id) {

   _max_lrg_id= max_lrg_id;

   // Force the Union-Find mapping to be at least this large

   _uf_map.extend(_max_lrg_id, 0);

   // Initialize it to be the ID mapping.

   for (uint i = 0; i < _max_lrg_id; ++i) {

     _uf_map.map(i, i);

   }

 }

 // Make all Nodes map directly to their final live range; no need for

 // the Union-Find mapping after this call.

 void LiveRangeMap::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);

     }

   }

 }

 // Like Find above, but no path compress, so bad asymptotic behavior

 uint LiveRangeMap::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 >= _max_lrg_id) {

     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;

 }

 //------------------------------Chaitin----------------------------------------

 PhaseChaitin::PhaseChaitin(uint unique, PhaseCFG &cfg, Matcher &matcher)

   : PhaseRegAlloc(unique, cfg, matcher,

 #ifndef PRODUCT

        print_chaitin_statistics

 #else

        NULL

 #endif

        )

   , _lrg_map(unique)

   , _live(0)

   , _spilled_once(Thread::current()->resource_area())

   , _spilled_twice(Thread::current()->resource_area())

   , _lo_degree(0), _lo_stk_degree(0), _hi_degree(0), _simplified(0)

   , _oldphi(unique)

 #ifndef PRODUCT

   , _trace_spilling(TraceSpilling || C->method_has_option("TraceSpilling"))

 #endif

 {

   NOT_PRODUCT( Compile::TracePhase t3("ctorChaitin", &_t_ctorChaitin, TimeCompiler); )

   _high_frequency_lrg = MIN2(float(OPTO_LRG_HIGH_FREQ), _cfg._outer_loop_freq);

   // Build a list of basic blocks, sorted by frequency

   _blks = NEW_RESOURCE_ARRAY( Block *, _cfg._num_blocks );

   // Experiment with sorting strategies to speed compilation

   double  cutoff = BLOCK_FREQUENCY(1.0); // Cutoff for high frequency bucket

   Block **buckets[NUMBUCKS];             // Array of buckets

   uint    buckcnt[NUMBUCKS];             // Array of bucket counters

   double  buckval[NUMBUCKS];             // Array of bucket value cutoffs

   for (uint i = 0; i < NUMBUCKS; i++) {

     buckets[i] = NEW_RESOURCE_ARRAY(Block *, _cfg._num_blocks);

     buckcnt[i] = 0;

     // Bump by three orders of magnitude each time

     cutoff *= 0.001;

     buckval[i] = cutoff;

     for (uint j = 0; j < _cfg._num_blocks; j++) {

       buckets[i][j] = NULL;

     }

   }

   // Sort blocks into buckets

   for (uint i = 0; i < _cfg._num_blocks; i++) {

     for (uint j = 0; j < NUMBUCKS; j++) {

       if ((j == NUMBUCKS - 1) || (_cfg._blocks[i]->_freq > buckval[j])) {

         // Assign block to end of list for appropriate bucket

         buckets[j][buckcnt[j]++] = _cfg._blocks[i];

         break; // kick out of inner loop

       }

     }

   }

   // Dump buckets into final block array

   uint blkcnt = 0;

   for (uint i = 0; i < NUMBUCKS; i++) {

     for (uint j = 0; j < buckcnt[i]; j++) {

       _blks[blkcnt++] = buckets[i][j];

     }

   }

   assert(blkcnt == _cfg._num_blocks, "Block array not totally filled");

 }

 //------------------------------Union------------------------------------------

 // union 2 sets together.

 void PhaseChaitin::Union( const Node *src_n, const Node *dst_n ) {

   uint src = _lrg_map.find(src_n);

   uint dst = _lrg_map.find(dst_n);

   assert(src, "");

   assert(dst, "");

   assert(src < _lrg_map.max_lrg_id(), "oob");

   assert(dst < _lrg_map.max_lrg_id(), "oob");

   assert(src < dst, "always union smaller");

   _lrg_map.uf_map(dst, src);

 }

 //------------------------------new_lrg----------------------------------------

 void PhaseChaitin::new_lrg(const Node *x, uint lrg) {

   // Make the Node->LRG mapping

   _lrg_map.extend(x->_idx,lrg);

   // Make the Union-Find mapping an identity function

   _lrg_map.uf_extend(lrg, lrg);

 }

 bool PhaseChaitin::clone_projs_shared(Block *b, uint idx, Node *con, Node *copy, uint max_lrg_id) {

   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->is_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, max_lrg_id);

   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 < _lrg_map.max_lrg_id(); i++) {

     uint lr = _lrg_map.uf_live_range_id(i);

     // Ignore unallocated live ranges

     if (!lr) {

       continue;

     }

     assert(lr <= i, "");

     _lrg_map.uf_map(i, ( lr == i ) ? j++ : _lrg_map.uf_live_range_id(lr));

   }

   // Now change the Node->LR mapping to reflect the compacted names

   uint unique = _lrg_map.size();

   for (i = 0; i < unique; i++) {

     uint lrg_id = _lrg_map.live_range_id(i);

     _lrg_map.map(i, _lrg_map.uf_live_range_id(lrg_id));

   }

   // Reset the Union-Find mapping

   _lrg_map.reset_uf_map(j);

 }

 void PhaseChaitin::Register_Allocate() {

   // Above the OLD FP (and in registers) are the incoming arguments.  Stack

   // slots in this area are called "arg_slots".  Above the NEW FP (and in

   // registers) is the outgoing argument area; above that is the spill/temp

   // area.  These are all "frame_slots".  Arg_slots start at the zero

   // stack_slots and count up to the known arg_size.  Frame_slots start at

   // the stack_slot #arg_size and go up.  After allocation I map stack

   // slots to actual offsets.  Stack-slots in the arg_slot area are biased

   // by the frame_size; stack-slots in the frame_slot area are biased by 0.

   _trip_cnt = 0;

   _alternate = 0;

   _matcher._allocation_started = true;

   ResourceArea split_arena;     // Arena for Split local resources

   ResourceArea live_arena;      // Arena for liveness & IFG info

   ResourceMark rm(&live_arena);

   // Need live-ness for the IFG; need the IFG for coalescing.  If the

   // liveness is JUST for coalescing, then I can get some mileage by renaming

   // all copy-related live ranges low and then using the max copy-related

   // live range as a cut-off for LIVE and the IFG.  In other words, I can

   // build a subset of LIVE and IFG just for copies.

   PhaseLive live(_cfg, _lrg_map.names(), &live_arena);

   // Need IFG for coalescing and coloring

   PhaseIFG ifg(&live_arena);

   _ifg = &ifg;

   // Come out of SSA world to the Named world.  Assign (virtual) registers to

   // Nodes.  Use the same register for all inputs and the output of PhiNodes

   // - effectively ending SSA form.  This requires either coalescing live

   // ranges or inserting copies.  For the moment, we insert "virtual copies"

   // - we pretend there is a copy prior to each Phi in predecessor blocks.

   // We will attempt to coalesce such "virtual copies" before we manifest

   // them for real.

   de_ssa();

 #ifdef ASSERT

   // Veify the graph before RA.

   verify(&live_arena);

 #endif

   {

     NOT_PRODUCT( Compile::TracePhase t3("computeLive", &_t_computeLive, TimeCompiler); )

     _live = NULL;                 // Mark live as being not available

     rm.reset_to_mark();           // Reclaim working storage

     IndexSet::reset_memory(C, &live_arena);

     ifg.init(_lrg_map.max_lrg_id()); // Empty IFG

     gather_lrg_masks( false );    // Collect LRG masks

     live.compute(_lrg_map.max_lrg_id()); // Compute liveness

     _live = &live;                // Mark LIVE as being available

   }

   // Base pointers are currently "used" by instructions which define new

   // derived pointers.  This makes base pointers live up to the where the

   // derived pointer is made, but not beyond.  Really, they need to be live

   // across any GC point where the derived value is live.  So this code looks

   // at all the GC points, and "stretches" the live range of any base pointer

   // to the GC point.

   if (stretch_base_pointer_live_ranges(&live_arena)) {

     NOT_PRODUCT(Compile::TracePhase t3("computeLive (sbplr)", &_t_computeLive, TimeCompiler);)

     // Since some live range stretched, I need to recompute live

     _live = NULL;

     rm.reset_to_mark();         // Reclaim working storage

     IndexSet::reset_memory(C, &live_arena);

     ifg.init(_lrg_map.max_lrg_id());

     gather_lrg_masks(false);

     live.compute(_lrg_map.max_lrg_id());

     _live = &live;

   }

   // Create the interference graph using virtual copies

   build_ifg_virtual();  // Include stack slots this time

   // Aggressive (but pessimistic) copy coalescing.

   // This pass works on virtual copies.  Any virtual copies which are not

   // coalesced get manifested as actual copies

   {

     // The IFG is/was triangular.  I am 'squaring it up' so Union can run

     // faster.  Union requires a 'for all' operation which is slow on the

     // triangular adjacency matrix (quick reminder: the IFG is 'sparse' -

     // meaning I can visit all the Nodes neighbors less than a Node in time

     // O(# of neighbors), but I have to visit all the Nodes greater than a

     // given Node and search them for an instance, i.e., time O(#MaxLRG)).

     _ifg->SquareUp();

     PhaseAggressiveCoalesce coalesce(*this);

     coalesce.coalesce_driver();

     // Insert un-coalesced copies.  Visit all Phis.  Where inputs to a Phi do

     // not match the Phi itself, insert a copy.

     coalesce.insert_copies(_matcher);

   }

   // After aggressive coalesce, attempt a first cut at coloring.

   // To color, we need the IFG and for that we need LIVE.

   {

     NOT_PRODUCT( Compile::TracePhase t3("computeLive", &_t_computeLive, TimeCompiler); )

     _live = NULL;

     rm.reset_to_mark();           // Reclaim working storage

     IndexSet::reset_memory(C, &live_arena);

     ifg.init(_lrg_map.max_lrg_id());

     gather_lrg_masks( true );

     live.compute(_lrg_map.max_lrg_id());

     _live = &live;

   }

   // Build physical interference graph

   uint must_spill = 0;

   must_spill = build_ifg_physical(&live_arena);

   // If we have a guaranteed spill, might as well spill now

   if (must_spill) {

     if(!_lrg_map.max_lrg_id()) {

       return;

     }

     // Bail out if unique gets too large (ie - unique > MaxNodeLimit)

     C->check_node_count(10*must_spill, "out of nodes before split");

     if (C->failing()) {

       return;

     }

     uint new_max_lrg_id = Split(_lrg_map.max_lrg_id(), &split_arena);  // Split spilling LRG everywhere

     _lrg_map.set_max_lrg_id(new_max_lrg_id);

     // Bail out if unique gets too large (ie - unique > MaxNodeLimit - 2*NodeLimitFudgeFactor)

     // or we failed to split

     C->check_node_count(2*NodeLimitFudgeFactor, "out of nodes after physical split");

     if (C->failing()) {

       return;

     }

     NOT_PRODUCT(C->verify_graph_edges();)

     compact();                  // Compact LRGs; return new lower max lrg

     {

       NOT_PRODUCT( Compile::TracePhase t3("computeLive", &_t_computeLive, TimeCompiler); )

       _live = NULL;

       rm.reset_to_mark();         // Reclaim working storage

       IndexSet::reset_memory(C, &live_arena);

       ifg.init(_lrg_map.max_lrg_id()); // Build a new interference graph

       gather_lrg_masks( true );   // Collect intersect mask

       live.compute(_lrg_map.max_lrg_id()); // Compute LIVE

       _live = &live;

     }

     build_ifg_physical(&live_arena);

     _ifg->SquareUp();

     _ifg->Compute_Effective_Degree();

     // Only do conservative coalescing if requested

     if (OptoCoalesce) {

       // Conservative (and pessimistic) copy coalescing of those spills

       PhaseConservativeCoalesce coalesce(*this);

       // If max live ranges greater than cutoff, don't color the stack.

       // This cutoff can be larger than below since it is only done once.

       coalesce.coalesce_driver();

     }

     _lrg_map.compress_uf_map_for_nodes();

 #ifdef ASSERT

     verify(&live_arena, true);

 #endif

   } else {

     ifg.SquareUp();

     ifg.Compute_Effective_Degree();

 #ifdef ASSERT

     set_was_low();

 #endif

   }

   // Prepare for Simplify & Select

   cache_lrg_info();           // Count degree of LRGs

   // Simplify the InterFerence Graph by removing LRGs of low degree.

   // LRGs of low degree are trivially colorable.

   Simplify();

   // Select colors by re-inserting LRGs back into the IFG in reverse order.

   // Return whether or not something spills.

   uint spills = Select( );

   // If we spill, split and recycle the entire thing

   while( spills ) {

     if( _trip_cnt++ > 24 ) {

       DEBUG_ONLY( dump_for_spill_split_recycle(); )

       if( _trip_cnt > 27 ) {

         C->record_method_not_compilable("failed spill-split-recycle sanity check");

         return;

       }

     }

     if (!_lrg_map.max_lrg_id()) {

       return;

     }

     uint new_max_lrg_id = Split(_lrg_map.max_lrg_id(), &split_arena);  // Split spilling LRG everywhere

     _lrg_map.set_max_lrg_id(new_max_lrg_id);

     // Bail out if unique gets too large (ie - unique > MaxNodeLimit - 2*NodeLimitFudgeFactor)

     C->check_node_count(2 * NodeLimitFudgeFactor, "out of nodes after split");

     if (C->failing()) {

       return;

     }

     compact(); // Compact LRGs; return new lower max lrg

     // Nuke the live-ness and interference graph and LiveRanGe info

     {

       NOT_PRODUCT( Compile::TracePhase t3("computeLive", &_t_computeLive, TimeCompiler); )

       _live = NULL;

       rm.reset_to_mark();         // Reclaim working storage

       IndexSet::reset_memory(C, &live_arena);

       ifg.init(_lrg_map.max_lrg_id());

       // Create LiveRanGe array.

       // Intersect register masks for all USEs and DEFs

       gather_lrg_masks(true);

       live.compute(_lrg_map.max_lrg_id());

       _live = &live;

     }

     must_spill = build_ifg_physical(&live_arena);

     _ifg->SquareUp();

     _ifg->Compute_Effective_Degree();

     // Only do conservative coalescing if requested

     if (OptoCoalesce) {

       // Conservative (and pessimistic) copy coalescing

       PhaseConservativeCoalesce coalesce(*this);

       // Check for few live ranges determines how aggressive coalesce is.

       coalesce.coalesce_driver();

     }

     _lrg_map.compress_uf_map_for_nodes();

 #ifdef ASSERT

     verify(&live_arena, true);

 #endif

     cache_lrg_info();           // Count degree of LRGs

     // Simplify the InterFerence Graph by removing LRGs of low degree.

     // LRGs of low degree are trivially colorable.

     Simplify();

     // Select colors by re-inserting LRGs back into the IFG in reverse order.

     // Return whether or not something spills.

     spills = Select();

   }

   // Count number of Simplify-Select trips per coloring success.

   _allocator_attempts += _trip_cnt + 1;

   _allocator_successes += 1;

   // Peephole remove copies

   post_allocate_copy_removal();

 #ifdef ASSERT

   // Veify the graph after RA.

   verify(&live_arena);

 #endif

   // max_reg is past the largest *register* used.

   // Convert that to a frame_slot number.

   if (_max_reg <= _matcher._new_SP) {

     _framesize = C->out_preserve_stack_slots();

   }

   else {

     _framesize = _max_reg -_matcher._new_SP;

   }

   assert((int)(_matcher._new_SP+_framesize) >= (int)_matcher._out_arg_limit, "framesize must be large enough");

   // This frame must preserve the required fp alignment

   _framesize = round_to(_framesize, Matcher::stack_alignment_in_slots());

   assert( _framesize >= 0 && _framesize <= 1000000, "sanity check" );

 #ifndef PRODUCT

   _total_framesize += _framesize;

   if ((int)_framesize > _max_framesize) {

     _max_framesize = _framesize;

   }

 #endif

   // Convert CISC spills

   fixup_spills();

   // Log regalloc results

   CompileLog* log = Compile::current()->log();

   if (log != NULL) {

     log->elem("regalloc attempts='%d' success='%d'", _trip_cnt, !C->failing());

   }

   if (C->failing()) {

     return;

   }

   NOT_PRODUCT(C->verify_graph_edges();)

   // Move important info out of the live_arena to longer lasting storage.

   alloc_node_regs(_lrg_map.size());

   for (uint i=0; i < _lrg_map.size(); i++) {

     if (_lrg_map.live_range_id(i)) { // Live range associated with Node?

       LRG &lrg = lrgs(_lrg_map.live_range_id(i));

       if (!lrg.alive()) {

         set_bad(i);

       } else if (lrg.num_regs() == 1) {

         set1(i, lrg.reg());

       } else {                  // Must be a register-set

         if (!lrg._fat_proj) {   // Must be aligned adjacent register set

           // Live ranges record the highest register in their mask.

           // We want the low register for the AD file writer's convenience.

           OptoReg::Name hi = lrg.reg(); // Get hi register

           OptoReg::Name lo = OptoReg::add(hi, (1-lrg.num_regs())); // Find lo

           // We have to use pair [lo,lo+1] even for wide vectors because

           // the rest of code generation works only with pairs. It is safe

           // since for registers encoding only 'lo' is used.

           // Second reg from pair is used in ScheduleAndBundle on SPARC where

           // vector max size is 8 which corresponds to registers pair.

           // It is also used in BuildOopMaps but oop operations are not

           // vectorized.

           set2(i, lo);

         } else {                // Misaligned; extract 2 bits

           OptoReg::Name hi = lrg.reg(); // Get hi register

           lrg.Remove(hi);       // Yank from mask

           int lo = lrg.mask().find_first_elem(); // Find lo

           set_pair(i, hi, lo);

         }

       }

       if( lrg._is_oop ) _node_oops.set(i);

     } else {

       set_bad(i);

     }

   }

   // Done!

   _live = NULL;

   _ifg = NULL;

   C->set_indexSet_arena(NULL);  // ResourceArea is at end of scope

 }

 //------------------------------de_ssa-----------------------------------------

 void PhaseChaitin::de_ssa() {

   // Set initial Names for all Nodes.  Most Nodes get the virtual register

   // number.  A few get the ZERO live range number.  These do not

   // get allocated, but instead rely on correct scheduling to ensure that

   // only one instance is simultaneously live at a time.

   uint lr_counter = 1;

   for( uint i = 0; i < _cfg._num_blocks; i++ ) {

     Block *b = _cfg._blocks[i];

     uint cnt = b->_nodes.size();

     // Handle all the normal Nodes in the block

     for( uint j = 0; j < cnt; j++ ) {

       Node *n = b->_nodes[j];

       // Pre-color to the zero live range, or pick virtual register

       const RegMask &rm = n->out_RegMask();

       _lrg_map.map(n->_idx, rm.is_NotEmpty() ? lr_counter++ : 0);

     }

   }

   // Reset the Union-Find mapping to be identity

   _lrg_map.reset_uf_map(lr_counter);

 }

 //------------------------------gather_lrg_masks-------------------------------

 // Gather LiveRanGe information, including register masks.  Modification of

 // cisc spillable in_RegMasks should not be done before AggressiveCoalesce.

 void PhaseChaitin::gather_lrg_masks( bool after_aggressive ) {

   // Nail down the frame pointer live range

   uint fp_lrg = _lrg_map.live_range_id(_cfg._root->in(1)->in(TypeFunc::FramePtr));

   lrgs(fp_lrg)._cost += 1e12;   // Cost is infinite

   // For all blocks

   for( uint i = 0; i < _cfg._num_blocks; i++ ) {

     Block *b = _cfg._blocks[i];

     // For all instructions

     for( uint j = 1; j < b->_nodes.size(); j++ ) {

       Node *n = b->_nodes[j];

       uint input_edge_start =1; // Skip control most nodes

       if( n->is_Mach() ) input_edge_start = n->as_Mach()->oper_input_base();

       uint idx = n->is_Copy();

       // Get virtual register number, same as LiveRanGe index

       uint vreg = _lrg_map.live_range_id(n);

       LRG &lrg = lrgs(vreg);

       if( vreg ) {              // No vreg means un-allocable (e.g. memory)

         // Collect has-copy bit

         if( idx ) {

           lrg._has_copy = 1;

           uint clidx = _lrg_map.live_range_id(n->in(idx));

           LRG &copy_src = lrgs(clidx);

           copy_src._has_copy = 1;

         }

         // Check for float-vs-int live range (used in register-pressure

         // calculations)

         const Type *n_type = n->bottom_type();

         if (n_type->is_floatingpoint())

           lrg._is_float = 1;

         // Check for twice prior spilling.  Once prior spilling might have

         // spilled 'soft', 2nd prior spill should have spilled 'hard' and

         // further spilling is unlikely to make progress.

         if( _spilled_once.test(n->_idx) ) {

           lrg._was_spilled1 = 1;

           if( _spilled_twice.test(n->_idx) )

             lrg._was_spilled2 = 1;

         }

 #ifndef PRODUCT

         if (trace_spilling() && lrg._def != NULL) {

           // collect defs for MultiDef printing

           if (lrg._defs == NULL) {

             lrg._defs = new (_ifg->_arena) GrowableArray<Node*>(_ifg->_arena, 2, 0, NULL);

             lrg._defs->append(lrg._def);

           }

           lrg._defs->append(n);

         }

 #endif

         // Check for a single def LRG; these can spill nicely

         // via rematerialization.  Flag as NULL for no def found

         // yet, or 'n' for single def or -1 for many defs.

         lrg._def = lrg._def ? NodeSentinel : n;

         // Limit result register mask to acceptable registers

         const RegMask &rm = n->out_RegMask();

         lrg.AND( rm );

         int ireg = n->ideal_reg();

         assert( !n->bottom_type()->isa_oop_ptr() || ireg == Op_RegP,

                 "oops must be in Op_RegP's" );

         // Check for vector live range (only if vector register is used).

         // On SPARC vector uses RegD which could be misaligned so it is not

         // processes as vector in RA.

         if (RegMask::is_vector(ireg))

           lrg._is_vector = 1;

         assert(n_type->isa_vect() == NULL || lrg._is_vector || ireg == Op_RegD,

                "vector must be in vector registers");

         // Check for bound register masks

         const RegMask &lrgmask = lrg.mask();

         if (lrgmask.is_bound(ireg))

           lrg._is_bound = 1;

         // Check for maximum frequency value

         if (lrg._maxfreq < b->_freq)

           lrg._maxfreq = b->_freq;

         // Check for oop-iness, or long/double

         // Check for multi-kill projection

         switch( ireg ) {

         case MachProjNode::fat_proj:

           // Fat projections have size equal to number of registers killed

           lrg.set_num_regs(rm.Size());

           lrg.set_reg_pressure(lrg.num_regs());

           lrg._fat_proj = 1;

           lrg._is_bound = 1;

           break;

         case Op_RegP:

 #ifdef _LP64

           lrg.set_num_regs(2);  // Size is 2 stack words

 #else

           lrg.set_num_regs(1);  // Size is 1 stack word

 #endif

           // Register pressure is tracked relative to the maximum values

           // suggested for that platform, INTPRESSURE and FLOATPRESSURE,

           // and relative to other types which compete for the same regs.

           //

           // The following table contains suggested values based on the

           // architectures as defined in each .ad file.

           // INTPRESSURE and FLOATPRESSURE may be tuned differently for

           // compile-speed or performance.

           // Note1:

           // SPARC and SPARCV9 reg_pressures are at 2 instead of 1

           // since .ad registers are defined as high and low halves.

           // These reg_pressure values remain compatible with the code

           // in is_high_pressure() which relates get_invalid_mask_size(),

           // Block::_reg_pressure and INTPRESSURE, FLOATPRESSURE.

           // Note2:

           // SPARC -d32 has 24 registers available for integral values,

           // but only 10 of these are safe for 64-bit longs.

           // Using set_reg_pressure(2) for both int and long means

           // the allocator will believe it can fit 26 longs into

           // registers.  Using 2 for longs and 1 for ints means the

           // allocator will attempt to put 52 integers into registers.

           // The settings below limit this problem to methods with

           // many long values which are being run on 32-bit SPARC.

           //

           // ------------------- reg_pressure --------------------

           // Each entry is reg_pressure_per_value,number_of_regs

           //         RegL  RegI  RegFlags   RegF RegD    INTPRESSURE  FLOATPRESSURE

           // IA32     2     1     1          1    1          6           6

           // IA64     1     1     1          1    1         50          41

           // SPARC    2     2     2          2    2         48 (24)     52 (26)

           // SPARCV9  2     2     2          2    2         48 (24)     52 (26)

           // AMD64    1     1     1          1    1         14          15

           // -----------------------------------------------------

 #if defined(SPARC)

           lrg.set_reg_pressure(2);  // use for v9 as well

 #else

           lrg.set_reg_pressure(1);  // normally one value per register

 #endif

           if( n_type->isa_oop_ptr() ) {

             lrg._is_oop = 1;

           }

           break;

         case Op_RegL:           // Check for long or double

         case Op_RegD:

           lrg.set_num_regs(2);

           // Define platform specific register pressure

 #if defined(SPARC) || defined(ARM)

           lrg.set_reg_pressure(2);

 #elif defined(IA32)

           if( ireg == Op_RegL ) {

             lrg.set_reg_pressure(2);

           } else {

             lrg.set_reg_pressure(1);

           }

 #else

           lrg.set_reg_pressure(1);  // normally one value per register

 #endif

           // If this def of a double forces a mis-aligned double,

           // flag as '_fat_proj' - really flag as allowing misalignment

           // AND changes how we count interferences.  A mis-aligned

           // double can interfere with TWO aligned pairs, or effectively

           // FOUR registers!

           if (rm.is_misaligned_pair()) {

             lrg._fat_proj = 1;

             lrg._is_bound = 1;

           }

           break;

         case Op_RegF:

         case Op_RegI:

         case Op_RegN:

         case Op_RegFlags:

         case 0:                 // not an ideal register

           lrg.set_num_regs(1);

 #ifdef SPARC

           lrg.set_reg_pressure(2);

 #else

           lrg.set_reg_pressure(1);

 #endif

           break;

         case Op_VecS:

           assert(Matcher::vector_size_supported(T_BYTE,4), "sanity");

           assert(RegMask::num_registers(Op_VecS) == RegMask::SlotsPerVecS, "sanity");

           lrg.set_num_regs(RegMask::SlotsPerVecS);

           lrg.set_reg_pressure(1);

           break;

         case Op_VecD:

           assert(Matcher::vector_size_supported(T_FLOAT,RegMask::SlotsPerVecD), "sanity");

           assert(RegMask::num_registers(Op_VecD) == RegMask::SlotsPerVecD, "sanity");

           assert(lrgmask.is_aligned_sets(RegMask::SlotsPerVecD), "vector should be aligned");

           lrg.set_num_regs(RegMask::SlotsPerVecD);

           lrg.set_reg_pressure(1);

           break;

         case Op_VecX:

           assert(Matcher::vector_size_supported(T_FLOAT,RegMask::SlotsPerVecX), "sanity");

           assert(RegMask::num_registers(Op_VecX) == RegMask::SlotsPerVecX, "sanity");

           assert(lrgmask.is_aligned_sets(RegMask::SlotsPerVecX), "vector should be aligned");

           lrg.set_num_regs(RegMask::SlotsPerVecX);

           lrg.set_reg_pressure(1);

           break;

         case Op_VecY:

           assert(Matcher::vector_size_supported(T_FLOAT,RegMask::SlotsPerVecY), "sanity");

           assert(RegMask::num_registers(Op_VecY) == RegMask::SlotsPerVecY, "sanity");

           assert(lrgmask.is_aligned_sets(RegMask::SlotsPerVecY), "vector should be aligned");

           lrg.set_num_regs(RegMask::SlotsPerVecY);

           lrg.set_reg_pressure(1);

           break;

         default:

           ShouldNotReachHere();

         }

       }

       // Now do the same for inputs

       uint cnt = n->req();

       // Setup for CISC SPILLING

       uint inp = (uint)AdlcVMDeps::Not_cisc_spillable;

       if( UseCISCSpill && after_aggressive ) {

         inp = n->cisc_operand();

         if( inp != (uint)AdlcVMDeps::Not_cisc_spillable )

           // Convert operand number to edge index number

           inp = n->as_Mach()->operand_index(inp);

       }

       // Prepare register mask for each input

       for( uint k = input_edge_start; k < cnt; k++ ) {

         uint vreg = _lrg_map.live_range_id(n->in(k));

         if (!vreg) {

           continue;

         }

         // If this instruction is CISC Spillable, add the flags

         // bit to its appropriate input

         if( UseCISCSpill && after_aggressive && inp == k ) {

 #ifndef PRODUCT

           if( TraceCISCSpill ) {

             tty->print("  use_cisc_RegMask: ");

             n->dump();

           }

 #endif

           n->as_Mach()->use_cisc_RegMask();

         }

         LRG &lrg = lrgs(vreg);

         // // Testing for floating point code shape

         // Node *test = n->in(k);

         // if( test->is_Mach() ) {

         //   MachNode *m = test->as_Mach();

         //   int  op = m->ideal_Opcode();

         //   if (n->is_Call() && (op == Op_AddF || op == Op_MulF) ) {

         //     int zzz = 1;

         //   }

         // }

         // Limit result register mask to acceptable registers.

         // Do not limit registers from uncommon uses before

         // AggressiveCoalesce.  This effectively pre-virtual-splits

         // around uncommon uses of common defs.

         const RegMask &rm = n->in_RegMask(k);

         if( !after_aggressive &&

           _cfg._bbs[n->in(k)->_idx]->_freq > 1000*b->_freq ) {

           // Since we are BEFORE aggressive coalesce, leave the register

           // mask untrimmed by the call.  This encourages more coalescing.

           // Later, AFTER aggressive, this live range will have to spill

           // but the spiller handles slow-path calls very nicely.

         } else {

           lrg.AND( rm );

         }

         // Check for bound register masks

         const RegMask &lrgmask = lrg.mask();

         int kreg = n->in(k)->ideal_reg();

         bool is_vect = RegMask::is_vector(kreg);

         assert(n->in(k)->bottom_type()->isa_vect() == NULL ||

                is_vect || kreg == Op_RegD,

                "vector must be in vector registers");

         if (lrgmask.is_bound(kreg))

           lrg._is_bound = 1;

         // If this use of a double forces a mis-aligned double,

         // flag as '_fat_proj' - really flag as allowing misalignment

         // AND changes how we count interferences.  A mis-aligned

         // double can interfere with TWO aligned pairs, or effectively

         // FOUR registers!

 #ifdef ASSERT

         if (is_vect) {

           assert(lrgmask.is_aligned_sets(lrg.num_regs()), "vector should be aligned");

           assert(!lrg._fat_proj, "sanity");

           assert(RegMask::num_registers(kreg) == lrg.num_regs(), "sanity");

         }

 #endif

         if (!is_vect && lrg.num_regs() == 2 && !lrg._fat_proj && rm.is_misaligned_pair()) {

           lrg._fat_proj = 1;

           lrg._is_bound = 1;

         }

         // if the LRG is an unaligned pair, we will have to spill

         // so clear the LRG's register mask if it is not already spilled

         if (!is_vect && !n->is_SpillCopy() &&

             (lrg._def == NULL || lrg.is_multidef() || !lrg._def->is_SpillCopy()) &&

             lrgmask.is_misaligned_pair()) {

           lrg.Clear();

         }

         // Check for maximum frequency value

         if( lrg._maxfreq < b->_freq )

           lrg._maxfreq = b->_freq;

       } // End for all allocated inputs

     } // end for all instructions

   } // end for all blocks

   // Final per-liverange setup

   for (uint i2 = 0; i2 < _lrg_map.max_lrg_id(); i2++) {

     LRG &lrg = lrgs(i2);

     assert(!lrg._is_vector || !lrg._fat_proj, "sanity");

     if (lrg.num_regs() > 1 && !lrg._fat_proj) {

       lrg.clear_to_sets();

     }

     lrg.compute_set_mask_size();

     if (lrg.not_free()) {      // Handle case where we lose from the start

       lrg.set_reg(OptoReg::Name(LRG::SPILL_REG));

       lrg._direct_conflict = 1;

     }

     lrg.set_degree(0);          // no neighbors in IFG yet

   }

 }

 //------------------------------set_was_low------------------------------------

 // Set the was-lo-degree bit.  Conservative coalescing should not change the

 // colorability of the graph.  If any live range was of low-degree before

 // coalescing, it should Simplify.  This call sets the was-lo-degree bit.

 // The bit is checked in Simplify.

 void PhaseChaitin::set_was_low() {

 #ifdef ASSERT

   for (uint i = 1; i < _lrg_map.max_lrg_id(); i++) {

     int size = lrgs(i).num_regs();

     uint old_was_lo = lrgs(i)._was_lo;

     lrgs(i)._was_lo = 0;

     if( lrgs(i).lo_degree() ) {

       lrgs(i)._was_lo = 1;      // Trivially of low degree

     } else {                    // Else check the Brigg's assertion

       // Brigg's observation is that the lo-degree neighbors of a

       // hi-degree live range will not interfere with the color choices

       // of said hi-degree live range.  The Simplify reverse-stack-coloring

       // order takes care of the details.  Hence you do not have to count

       // low-degree neighbors when determining if this guy colors.

       int briggs_degree = 0;

       IndexSet *s = _ifg->neighbors(i);

       IndexSetIterator elements(s);

       uint lidx;

       while((lidx = elements.next()) != 0) {

         if( !lrgs(lidx).lo_degree() )

           briggs_degree += MAX2(size,lrgs(lidx).num_regs());

       }

       if( briggs_degree < lrgs(i).degrees_of_freedom() )

         lrgs(i)._was_lo = 1;    // Low degree via the briggs assertion

     }

     assert(old_was_lo <= lrgs(i)._was_lo, "_was_lo may not decrease");

   }

 #endif

 }

 #define REGISTER_CONSTRAINED 16

 //------------------------------cache_lrg_info---------------------------------

 // Compute cost/area ratio, in case we spill.  Build the lo-degree list.

 void PhaseChaitin::cache_lrg_info( ) {

   for (uint i = 1; i < _lrg_map.max_lrg_id(); i++) {

     LRG &lrg = lrgs(i);

     // Check for being of low degree: means we can be trivially colored.

     // Low degree, dead or must-spill guys just get to simplify right away

     if( lrg.lo_degree() ||

        !lrg.alive() ||

         lrg._must_spill ) {

       // Split low degree list into those guys that must get a

       // register and those that can go to register or stack.

       // The idea is LRGs that can go register or stack color first when

       // they have a good chance of getting a register.  The register-only

       // lo-degree live ranges always get a register.

       OptoReg::Name hi_reg = lrg.mask().find_last_elem();

       if( OptoReg::is_stack(hi_reg)) { // Can go to stack?

         lrg._next = _lo_stk_degree;

         _lo_stk_degree = i;

       } else {

         lrg._next = _lo_degree;

         _lo_degree = i;

       }

     } else {                    // Else high degree

       lrgs(_hi_degree)._prev = i;

       lrg._next = _hi_degree;

       lrg._prev = 0;

       _hi_degree = i;

     }

   }

 }

 //------------------------------Pre-Simplify-----------------------------------

 // Simplify the IFG by removing LRGs of low degree that have NO copies

 void PhaseChaitin::Pre_Simplify( ) {

   // Warm up the lo-degree no-copy list

   int lo_no_copy = 0;

   for (uint i = 1; i < _lrg_map.max_lrg_id(); i++) {

     if ((lrgs(i).lo_degree() && !lrgs(i)._has_copy) ||

         !lrgs(i).alive() ||

         lrgs(i)._must_spill) {

       lrgs(i)._next = lo_no_copy;

       lo_no_copy = i;

     }

   }

   while( lo_no_copy ) {

     uint lo = lo_no_copy;

     lo_no_copy = lrgs(lo)._next;

     int size = lrgs(lo).num_regs();

     // Put the simplified guy on the simplified list.

     lrgs(lo)._next = _simplified;

     _simplified = lo;

     // Yank this guy from the IFG.

     IndexSet *adj = _ifg->remove_node( lo );

     // If any neighbors' degrees fall below their number of

     // allowed registers, then put that neighbor on the low degree

     // list.  Note that 'degree' can only fall and 'numregs' is

     // unchanged by this action.  Thus the two are equal at most once,

     // so LRGs hit the lo-degree worklists at most once.

     IndexSetIterator elements(adj);

     uint neighbor;

     while ((neighbor = elements.next()) != 0) {

       LRG *n = &lrgs(neighbor);

       assert( _ifg->effective_degree(neighbor) == n->degree(), "" );

       // Check for just becoming of-low-degree

       if( n->just_lo_degree() && !n->_has_copy ) {

         assert(!(*_ifg->_yanked)[neighbor],"Cannot move to lo degree twice");

         // Put on lo-degree list

         n->_next = lo_no_copy;

         lo_no_copy = neighbor;

       }

     }

   } // End of while lo-degree no_copy worklist not empty

   // No more lo-degree no-copy live ranges to simplify

 }

 //------------------------------Simplify---------------------------------------

 // Simplify the IFG by removing LRGs of low degree.

 void PhaseChaitin::Simplify( ) {

   while( 1 ) {                  // Repeat till simplified it all

     // May want to explore simplifying lo_degree before _lo_stk_degree.

     // This might result in more spills coloring into registers during

     // Select().

     while( _lo_degree || _lo_stk_degree ) {

       // If possible, pull from lo_stk first

       uint lo;

       if( _lo_degree ) {

         lo = _lo_degree;

         _lo_degree = lrgs(lo)._next;

       } else {

         lo = _lo_stk_degree;

         _lo_stk_degree = lrgs(lo)._next;

       }

       // Put the simplified guy on the simplified list.

       lrgs(lo)._next = _simplified;

       _simplified = lo;

       // If this guy is "at risk" then mark his current neighbors

       if( lrgs(lo)._at_risk ) {

         IndexSetIterator elements(_ifg->neighbors(lo));

         uint datum;

         while ((datum = elements.next()) != 0) {

           lrgs(datum)._risk_bias = lo;

         }

       }

       // Yank this guy from the IFG.

       IndexSet *adj = _ifg->remove_node( lo );

       // If any neighbors' degrees fall below their number of

       // allowed registers, then put that neighbor on the low degree

       // list.  Note that 'degree' can only fall and 'numregs' is

       // unchanged by this action.  Thus the two are equal at most once,

       // so LRGs hit the lo-degree worklist at most once.

       IndexSetIterator elements(adj);

       uint neighbor;

       while ((neighbor = elements.next()) != 0) {

         LRG *n = &lrgs(neighbor);

 #ifdef ASSERT

         if( VerifyOpto || VerifyRegisterAllocator ) {

           assert( _ifg->effective_degree(neighbor) == n->degree(), "" );

         }

 #endif

         // Check for just becoming of-low-degree just counting registers.

         // _must_spill live ranges are already on the low degree list.

         if( n->just_lo_degree() && !n->_must_spill ) {

           assert(!(*_ifg->_yanked)[neighbor],"Cannot move to lo degree twice");

           // Pull from hi-degree list

           uint prev = n->_prev;

           uint next = n->_next;

           if( prev ) lrgs(prev)._next = next;

           else _hi_degree = next;

           lrgs(next)._prev = prev;

           n->_next = _lo_degree;

           _lo_degree = neighbor;

         }

       }

     } // End of while lo-degree/lo_stk_degree worklist not empty

     // Check for got everything: is hi-degree list empty?

     if( !_hi_degree ) break;

     // Time to pick a potential spill guy

     uint lo_score = _hi_degree;

     double score = lrgs(lo_score).score();

     double area = lrgs(lo_score)._area;

     double cost = lrgs(lo_score)._cost;

     bool bound = lrgs(lo_score)._is_bound;

     // Find cheapest guy

     debug_only( int lo_no_simplify=0; );

     for( uint i = _hi_degree; i; i = lrgs(i)._next ) {

       assert( !(*_ifg->_yanked)[i], "" );

       // It's just vaguely possible to move hi-degree to lo-degree without

       // going through a just-lo-degree stage: If you remove a double from

       // a float live range it's degree will drop by 2 and you can skip the

       // just-lo-degree stage.  It's very rare (shows up after 5000+ methods

       // in -Xcomp of Java2Demo).  So just choose this guy to simplify next.

       if( lrgs(i).lo_degree() ) {

         lo_score = i;

         break;

       }

       debug_only( if( lrgs(i)._was_lo ) lo_no_simplify=i; );

       double iscore = lrgs(i).score();

       double iarea = lrgs(i)._area;

       double icost = lrgs(i)._cost;

       bool ibound = lrgs(i)._is_bound;

       // Compare cost/area of i vs cost/area of lo_score.  Smaller cost/area

       // wins.  Ties happen because all live ranges in question have spilled

       // a few times before and the spill-score adds a huge number which

       // washes out the low order bits.  We are choosing the lesser of 2

       // evils; in this case pick largest area to spill.

       // Ties also happen when live ranges are defined and used only inside

       // one block. In which case their area is 0 and score set to max.

       // In such case choose bound live range over unbound to free registers

       // or with smaller cost to spill.

       if( iscore < score ||

           (iscore == score && iarea > area && lrgs(lo_score)._was_spilled2) ||

           (iscore == score && iarea == area &&

            ( (ibound && !bound) || ibound == bound && (icost < cost) )) ) {

         lo_score = i;

         score = iscore;

         area = iarea;

         cost = icost;

         bound = ibound;

       }

     }

     LRG *lo_lrg = &lrgs(lo_score);

     // The live range we choose for spilling is either hi-degree, or very

     // rarely it can be low-degree.  If we choose a hi-degree live range

     // there better not be any lo-degree choices.

     assert( lo_lrg->lo_degree() || !lo_no_simplify, "Live range was lo-degree before coalesce; should simplify" );

     // Pull from hi-degree list

     uint prev = lo_lrg->_prev;

     uint next = lo_lrg->_next;

     if( prev ) lrgs(prev)._next = next;

     else _hi_degree = next;

     lrgs(next)._prev = prev;

     // Jam him on the lo-degree list, despite his high degree.

     // Maybe he'll get a color, and maybe he'll spill.

     // Only Select() will know.

     lrgs(lo_score)._at_risk = true;

     _lo_degree = lo_score;

     lo_lrg->_next = 0;

   } // End of while not simplified everything

 }

 //------------------------------is_legal_reg-----------------------------------

 // Is 'reg' register legal for 'lrg'?

 static bool is_legal_reg(LRG &lrg, OptoReg::Name reg, int chunk) {

   if (reg >= chunk && reg < (chunk + RegMask::CHUNK_SIZE) &&

       lrg.mask().Member(OptoReg::add(reg,-chunk))) {

     // RA uses OptoReg which represent the highest element of a registers set.

     // For example, vectorX (128bit) on x86 uses [XMM,XMMb,XMMc,XMMd] set

     // in which XMMd is used by RA to represent such vectors. A double value

     // uses [XMM,XMMb] pairs and XMMb is used by RA for it.

     // The register mask uses largest bits set of overlapping register sets.

     // On x86 with AVX it uses 8 bits for each XMM registers set.

     //

     // The 'lrg' already has cleared-to-set register mask (done in Select()

     // before calling choose_color()). Passing mask.Member(reg) check above

     // indicates that the size (num_regs) of 'reg' set is less or equal to

     // 'lrg' set size.

     // For set size 1 any register which is member of 'lrg' mask is legal.

     if (lrg.num_regs()==1)

       return true;

     // For larger sets only an aligned register with the same set size is legal.

     int mask = lrg.num_regs()-1;

     if ((reg&mask) == mask)

       return true;

   }

   return false;

 }

 //------------------------------bias_color-------------------------------------

 // Choose a color using the biasing heuristic

 OptoReg::Name PhaseChaitin::bias_color( LRG &lrg, int chunk ) {

   // Check for "at_risk" LRG's

   uint risk_lrg = _lrg_map.find(lrg._risk_bias);

   if( risk_lrg != 0 ) {

     // Walk the colored neighbors of the "at_risk" candidate

     // Choose a color which is both legal and already taken by a neighbor

     // of the "at_risk" candidate in order to improve the chances of the

     // "at_risk" candidate of coloring

     IndexSetIterator elements(_ifg->neighbors(risk_lrg));

     uint datum;

     while ((datum = elements.next()) != 0) {

       OptoReg::Name reg = lrgs(datum).reg();

       // If this LRG's register is legal for us, choose it

       if (is_legal_reg(lrg, reg, chunk))

         return reg;

     }

   }

   uint copy_lrg = _lrg_map.find(lrg._copy_bias);

   if( copy_lrg != 0 ) {

     // If he has a color,

     if( !(*(_ifg->_yanked))[copy_lrg] ) {

       OptoReg::Name reg = lrgs(copy_lrg).reg();

       //  And it is legal for you,

       if (is_legal_reg(lrg, reg, chunk))

         return reg;

     } else if( chunk == 0 ) {

       // Choose a color which is legal for him

       RegMask tempmask = lrg.mask();

       tempmask.AND(lrgs(copy_lrg).mask());

       tempmask.clear_to_sets(lrg.num_regs());

       OptoReg::Name reg = tempmask.find_first_set(lrg.num_regs());

       if (OptoReg::is_valid(reg))

         return reg;

     }

   }

   // If no bias info exists, just go with the register selection ordering

   if (lrg._is_vector || lrg.num_regs() == 2) {

     // Find an aligned set

     return OptoReg::add(lrg.mask().find_first_set(lrg.num_regs()),chunk);

   }

   // CNC - Fun hack.  Alternate 1st and 2nd selection.  Enables post-allocate

   // copy removal to remove many more copies, by preventing a just-assigned

   // register from being repeatedly assigned.

   OptoReg::Name reg = lrg.mask().find_first_elem();

   if( (++_alternate & 1) && OptoReg::is_valid(reg) ) {

     // This 'Remove; find; Insert' idiom is an expensive way to find the

     // SECOND element in the mask.

     lrg.Remove(reg);

     OptoReg::Name reg2 = lrg.mask().find_first_elem();

     lrg.Insert(reg);

     if( OptoReg::is_reg(reg2))

       reg = reg2;

   }

   return OptoReg::add( reg, chunk );

 }

 //------------------------------choose_color-----------------------------------

 // Choose a color in the current chunk

 OptoReg::Name PhaseChaitin::choose_color( LRG &lrg, int chunk ) {

   assert( C->in_preserve_stack_slots() == 0 || chunk != 0 || lrg._is_bound || lrg.mask().is_bound1() || !lrg.mask().Member(OptoReg::Name(_matcher._old_SP-1)), "must not allocate stack0 (inside preserve area)");

   assert(C->out_preserve_stack_slots() == 0 || chunk != 0 || lrg._is_bound || lrg.mask().is_bound1() || !lrg.mask().Member(OptoReg::Name(_matcher._old_SP+0)), "must not allocate stack0 (inside preserve area)");

   if( lrg.num_regs() == 1 ||    // Common Case

       !lrg._fat_proj )          // Aligned+adjacent pairs ok

     // Use a heuristic to "bias" the color choice

     return bias_color(lrg, chunk);

   assert(!lrg._is_vector, "should be not vector here" );

   assert( lrg.num_regs() >= 2, "dead live ranges do not color" );

   // Fat-proj case or misaligned double argument.

   assert(lrg.compute_mask_size() == lrg.num_regs() ||

          lrg.num_regs() == 2,"fat projs exactly color" );

   assert( !chunk, "always color in 1st chunk" );

   // Return the highest element in the set.

   return lrg.mask().find_last_elem();

 }

 //------------------------------Select-----------------------------------------

 // Select colors by re-inserting LRGs back into the IFG.  LRGs are re-inserted

 // in reverse order of removal.  As long as nothing of hi-degree was yanked,

 // everything going back is guaranteed a color.  Select that color.  If some

 // hi-degree LRG cannot get a color then we record that we must spill.

 uint PhaseChaitin::Select( ) {

   uint spill_reg = LRG::SPILL_REG;

   _max_reg = OptoReg::Name(0);  // Past max register used

   while( _simplified ) {

     // Pull next LRG from the simplified list - in reverse order of removal

     uint lidx = _simplified;

     LRG *lrg = &lrgs(lidx);

     _simplified = lrg->_next;

 #ifndef PRODUCT

     if (trace_spilling()) {

       ttyLocker ttyl;

       tty->print_cr("L%d selecting degree %d degrees_of_freedom %d", lidx, lrg->degree(),

                     lrg->degrees_of_freedom());

       lrg->dump();

     }

 #endif

     // Re-insert into the IFG

     _ifg->re_insert(lidx);

     if( !lrg->alive() ) continue;

     // capture allstackedness flag before mask is hacked

     const int is_allstack = lrg->mask().is_AllStack();

     // Yeah, yeah, yeah, I know, I know.  I can refactor this

     // to avoid the GOTO, although the refactored code will not

     // be much clearer.  We arrive here IFF we have a stack-based

     // live range that cannot color in the current chunk, and it

     // has to move into the next free stack chunk.

     int chunk = 0;              // Current chunk is first chunk

     retry_next_chunk:

     // Remove neighbor colors

     IndexSet *s = _ifg->neighbors(lidx);

     debug_only(RegMask orig_mask = lrg->mask();)

     IndexSetIterator elements(s);

     uint neighbor;

     while ((neighbor = elements.next()) != 0) {

       // Note that neighbor might be a spill_reg.  In this case, exclusion

       // of its color will be a no-op, since the spill_reg chunk is in outer

       // space.  Also, if neighbor is in a different chunk, this exclusion

       // will be a no-op.  (Later on, if lrg runs out of possible colors in

       // its chunk, a new chunk of color may be tried, in which case

       // examination of neighbors is started again, at retry_next_chunk.)

       LRG &nlrg = lrgs(neighbor);

       OptoReg::Name nreg = nlrg.reg();

       // Only subtract masks in the same chunk

       if( nreg >= chunk && nreg < chunk + RegMask::CHUNK_SIZE ) {

 #ifndef PRODUCT

         uint size = lrg->mask().Size();

         RegMask rm = lrg->mask();

 #endif

         lrg->SUBTRACT(nlrg.mask());

 #ifndef PRODUCT

         if (trace_spilling() && lrg->mask().Size() != size) {

           ttyLocker ttyl;

           tty->print("L%d ", lidx);

           rm.dump();

           tty->print(" intersected L%d ", neighbor);

           nlrg.mask().dump();

           tty->print(" removed ");

           rm.SUBTRACT(lrg->mask());

           rm.dump();

           tty->print(" leaving ");

           lrg->mask().dump();

           tty->cr();

         }

 #endif

       }

     }

     //assert(is_allstack == lrg->mask().is_AllStack(), "nbrs must not change AllStackedness");

     // Aligned pairs need aligned masks

     assert(!lrg->_is_vector || !lrg->_fat_proj, "sanity");

     if (lrg->num_regs() > 1 && !lrg->_fat_proj) {

       lrg->clear_to_sets();

     }

     // Check if a color is available and if so pick the color

     OptoReg::Name reg = choose_color( *lrg, chunk );

 #ifdef SPARC

     debug_only(lrg->compute_set_mask_size());

     assert(lrg->num_regs() < 2 || lrg->is_bound() || is_even(reg-1), "allocate all doubles aligned");

 #endif

     //---------------

     // If we fail to color and the AllStack flag is set, trigger

     // a chunk-rollover event

     if(!OptoReg::is_valid(OptoReg::add(reg,-chunk)) && is_allstack) {

       // Bump register mask up to next stack chunk

       chunk += RegMask::CHUNK_SIZE;

       lrg->Set_All();

       goto retry_next_chunk;

     }

     //---------------

     // Did we get a color?

     else if( OptoReg::is_valid(reg)) {

 #ifndef PRODUCT

       RegMask avail_rm = lrg->mask();

 #endif

       // Record selected register

       lrg->set_reg(reg);

       if( reg >= _max_reg )     // Compute max register limit

         _max_reg = OptoReg::add(reg,1);

       // Fold reg back into normal space

       reg = OptoReg::add(reg,-chunk);

       // If the live range is not bound, then we actually had some choices

       // to make.  In this case, the mask has more bits in it than the colors

       // chosen.  Restrict the mask to just what was picked.

       int n_regs = lrg->num_regs();

       assert(!lrg->_is_vector || !lrg->_fat_proj, "sanity");

       if (n_regs == 1 || !lrg->_fat_proj) {

         assert(!lrg->_is_vector || n_regs <= RegMask::SlotsPerVecY, "sanity");

         lrg->Clear();           // Clear the mask

         lrg->Insert(reg);       // Set regmask to match selected reg

         // For vectors and pairs, also insert the low bit of the pair

         for (int i = 1; i < n_regs; i++)

           lrg->Insert(OptoReg::add(reg,-i));

         lrg->set_mask_size(n_regs);

       } else {                  // Else fatproj

         // mask must be equal to fatproj bits, by definition

       }

 #ifndef PRODUCT

       if (trace_spilling()) {

         ttyLocker ttyl;

         tty->print("L%d selected ", lidx);

         lrg->mask().dump();

         tty->print(" from ");

         avail_rm.dump();

         tty->cr();

       }

 #endif

       // Note that reg is the highest-numbered register in the newly-bound mask.

     } // end color available case

     //---------------

     // Live range is live and no colors available

     else {

       assert( lrg->alive(), "" );

       assert( !lrg->_fat_proj || lrg->is_multidef() ||

               lrg->_def->outcnt() > 0, "fat_proj cannot spill");

       assert( !orig_mask.is_AllStack(), "All Stack does not spill" );

       // Assign the special spillreg register

       lrg->set_reg(OptoReg::Name(spill_reg++));

       // Do not empty the regmask; leave mask_size lying around

       // for use during Spilling

 #ifndef PRODUCT

       if( trace_spilling() ) {

         ttyLocker ttyl;

         tty->print("L%d spilling with neighbors: ", lidx);

         s->dump();

         debug_only(tty->print(" original mask: "));

         debug_only(orig_mask.dump());

         dump_lrg(lidx);

       }

 #endif

     } // end spill case

   }

   return spill_reg-LRG::SPILL_REG;      // Return number of spills

 }

 //------------------------------copy_was_spilled-------------------------------

 // Copy 'was_spilled'-edness from the source Node to the dst Node.

 void PhaseChaitin::copy_was_spilled( Node *src, Node *dst ) {

   if( _spilled_once.test(src->_idx) ) {

     _spilled_once.set(dst->_idx);

     lrgs(_lrg_map.find(dst))._was_spilled1 = 1;

     if( _spilled_twice.test(src->_idx) ) {

       _spilled_twice.set(dst->_idx);

       lrgs(_lrg_map.find(dst))._was_spilled2 = 1;

     }

   }

 }

 //------------------------------set_was_spilled--------------------------------

 // Set the 'spilled_once' or 'spilled_twice' flag on a node.

 void PhaseChaitin::set_was_spilled( Node *n ) {

   if( _spilled_once.test_set(n->_idx) )

     _spilled_twice.set(n->_idx);

 }

 //------------------------------fixup_spills-----------------------------------

 // Convert Ideal spill instructions into proper FramePtr + offset Loads and

 // Stores.  Use-def chains are NOT preserved, but Node->LRG->reg maps are.

 void PhaseChaitin::fixup_spills() {

   // This function does only cisc spill work.

   if( !UseCISCSpill ) return;

   NOT_PRODUCT( Compile::TracePhase t3("fixupSpills", &_t_fixupSpills, TimeCompiler); )

   // Grab the Frame Pointer

   Node *fp = _cfg._broot->head()->in(1)->in(TypeFunc::FramePtr);

   // For all blocks

   for( uint i = 0; i < _cfg._num_blocks; i++ ) {

     Block *b = _cfg._blocks[i];

     // For all instructions in block

     uint last_inst = b->end_idx();

     for( uint j = 1; j <= last_inst; j++ ) {

       Node *n = b->_nodes[j];

       // Dead instruction???

       assert( n->outcnt() != 0 ||// Nothing dead after post alloc

               C->top() == n ||  // Or the random TOP node

               n->is_Proj(),     // Or a fat-proj kill node

               "No dead instructions after post-alloc" );

       int inp = n->cisc_operand();

       if( inp != AdlcVMDeps::Not_cisc_spillable ) {

         // Convert operand number to edge index number

         MachNode *mach = n->as_Mach();

         inp = mach->operand_index(inp);

         Node *src = n->in(inp);   // Value to load or store

         LRG &lrg_cisc = lrgs(_lrg_map.find_const(src));

         OptoReg::Name src_reg = lrg_cisc.reg();

         // Doubles record the HIGH register of an adjacent pair.

         src_reg = OptoReg::add(src_reg,1-lrg_cisc.num_regs());

         if( OptoReg::is_stack(src_reg) ) { // If input is on stack

           // This is a CISC Spill, get stack offset and construct new node

 #ifndef PRODUCT

           if( TraceCISCSpill ) {

             tty->print("    reg-instr:  ");

             n->dump();

           }

 #endif

           int stk_offset = reg2offset(src_reg);

           // Bailout if we might exceed node limit when spilling this instruction

           C->check_node_count(0, "out of nodes fixing spills");

           if (C->failing())  return;

           // Transform node

           MachNode *cisc = mach->cisc_version(stk_offset, C)->as_Mach();

           cisc->set_req(inp,fp);          // Base register is frame pointer

           if( cisc->oper_input_base() > 1 && mach->oper_input_base() <= 1 ) {

             assert( cisc->oper_input_base() == 2, "Only adding one edge");

             cisc->ins_req(1,src);         // Requires a memory edge

           }

           b->_nodes.map(j,cisc);          // Insert into basic block

           n->subsume_by(cisc, C); // Correct graph

           //

           ++_used_cisc_instructions;

 #ifndef PRODUCT

           if( TraceCISCSpill ) {

             tty->print("    cisc-instr: ");

             cisc->dump();

           }

 #endif

         } else {

 #ifndef PRODUCT

           if( TraceCISCSpill ) {

             tty->print("    using reg-instr: ");

             n->dump();

           }

 #endif

           ++_unused_cisc_instructions;    // input can be on stack

         }

       }

     } // End of for all instructions

   } // End of for all blocks

 }

 //------------------------------find_base_for_derived--------------------------

 // Helper to stretch above; recursively discover the base Node for a

 // given derived Node.  Easy for AddP-related machine nodes, but needs

 // to be recursive for derived Phis.

 Node *PhaseChaitin::find_base_for_derived( Node **derived_base_map, Node *derived, uint &maxlrg ) {

   // See if already computed; if so return it

   if( derived_base_map[derived->_idx] )

     return derived_base_map[derived->_idx];

   // See if this happens to be a base.

   // NOTE: we use TypePtr instead of TypeOopPtr because we can have

   // pointers derived from NULL!  These are always along paths that

   // can't happen at run-time but the optimizer cannot deduce it so

   // we have to handle it gracefully.

   assert(!derived->bottom_type()->isa_narrowoop() ||

           derived->bottom_type()->make_ptr()->is_ptr()->_offset == 0, "sanity");

   const TypePtr *tj = derived->bottom_type()->isa_ptr();

   // If its an OOP with a non-zero offset, then it is derived.

   if( tj == NULL || tj->_offset == 0 ) {

     derived_base_map[derived->_idx] = derived;

     return derived;

   }

   // Derived is NULL+offset?  Base is NULL!

   if( derived->is_Con() ) {

     Node *base = _matcher.mach_null();

     assert(base != NULL, "sanity");

     if (base->in(0) == NULL) {

       // Initialize it once and make it shared:

       // set control to _root and place it into Start block

       // (where top() node is placed).

       base->init_req(0, _cfg._root);

       Block *startb = _cfg._bbs[C->top()->_idx];

       startb->_nodes.insert(startb->find_node(C->top()), base );

       _cfg._bbs.map( base->_idx, startb );

       assert(_lrg_map.live_range_id(base) == 0, "should not have LRG yet");

     }

     if (_lrg_map.live_range_id(base) == 0) {

       new_lrg(base, maxlrg++);

     }

     assert(base->in(0) == _cfg._root &&

            _cfg._bbs[base->_idx] == _cfg._bbs[C->top()->_idx], "base NULL should be shared");

     derived_base_map[derived->_idx] = base;

     return base;

   }

   // Check for AddP-related opcodes

   if (!derived->is_Phi()) {

     assert(derived->as_Mach()->ideal_Opcode() == Op_AddP, err_msg_res("but is: %s", derived->Name()));

     Node *base = derived->in(AddPNode::Base);

     derived_base_map[derived->_idx] = base;

     return base;

   }

   // Recursively find bases for Phis.

   // First check to see if we can avoid a base Phi here.

   Node *base = find_base_for_derived( derived_base_map, derived->in(1),maxlrg);

   uint i;

   for( i = 2; i < derived->req(); i++ )

     if( base != find_base_for_derived( derived_base_map,derived->in(i),maxlrg))

       break;

   // Went to the end without finding any different bases?

   if( i == derived->req() ) {   // No need for a base Phi here

     derived_base_map[derived->_idx] = base;

     return base;

   }

   // Now we see we need a base-Phi here to merge the bases

   const Type *t = base->bottom_type();

   base = new (C) PhiNode( derived->in(0), t );

   for( i = 1; i < derived->req(); i++ ) {

     base->init_req(i, find_base_for_derived(derived_base_map, derived->in(i), maxlrg));

     t = t->meet(base->in(i)->bottom_type());

   }

   base->as_Phi()->set_type(t);

   // Search the current block for an existing base-Phi

   Block *b = _cfg._bbs[derived->_idx];

   for( i = 1; i <= b->end_idx(); i++ ) {// Search for matching Phi

     Node *phi = b->_nodes[i];

     if( !phi->is_Phi() ) {      // Found end of Phis with no match?

       b->_nodes.insert( i, base ); // Must insert created Phi here as base

       _cfg._bbs.map( base->_idx, b );

       new_lrg(base,maxlrg++);

       break;

     }

     // See if Phi matches.

     uint j;

     for( j = 1; j < base->req(); j++ )

       if( phi->in(j) != base->in(j) &&

           !(phi->in(j)->is_Con() && base->in(j)->is_Con()) ) // allow different NULLs

         break;

     if( j == base->req() ) {    // All inputs match?

       base = phi;               // Then use existing 'phi' and drop 'base'

       break;

     }

   }

   // Cache info for later passes

   derived_base_map[derived->_idx] = base;

   return base;

 }

 //------------------------------stretch_base_pointer_live_ranges---------------

 // At each Safepoint, insert extra debug edges for each pair of derived value/

 // base pointer that is live across the Safepoint for oopmap building.  The

 // edge pairs get added in after sfpt->jvmtail()->oopoff(), but are in the

 // required edge set.

 bool PhaseChaitin::stretch_base_pointer_live_ranges(ResourceArea *a) {

   int must_recompute_live = false;

   uint maxlrg = _lrg_map.max_lrg_id();

   Node **derived_base_map = (Node**)a->Amalloc(sizeof(Node*)*C->unique());

   memset( derived_base_map, 0, sizeof(Node*)*C->unique() );

   // For all blocks in RPO do...

   for( uint i=0; i<_cfg._num_blocks; i++ ) {

     Block *b = _cfg._blocks[i];

     // Note use of deep-copy constructor.  I cannot hammer the original

     // liveout bits, because they are needed by the following coalesce pass.

     IndexSet liveout(_live->live(b));

     for( uint j = b->end_idx() + 1; j > 1; j-- ) {

       Node *n = b->_nodes[j-1];

       // Pre-split compares of loop-phis.  Loop-phis form a cycle we would

       // like to see in the same register.  Compare uses the loop-phi and so

       // extends its live range BUT cannot be part of the cycle.  If this

       // extended live range overlaps with the update of the loop-phi value

       // we need both alive at the same time -- which requires at least 1

       // copy.  But because Intel has only 2-address registers we end up with

       // at least 2 copies, one before the loop-phi update instruction and

       // one after.  Instead we split the input to the compare just after the

       // phi.

       if( n->is_Mach() && n->as_Mach()->ideal_Opcode() == Op_CmpI ) {

         Node *phi = n->in(1);

         if( phi->is_Phi() && phi->as_Phi()->region()->is_Loop() ) {

           Block *phi_block = _cfg._bbs[phi->_idx];

           if( _cfg._bbs[phi_block->pred(2)->_idx] == b ) {

             const RegMask *mask = C->matcher()->idealreg2spillmask[Op_RegI];

             Node *spill = new (C) MachSpillCopyNode( phi, *mask, *mask );

             insert_proj( phi_block, 1, spill, maxlrg++ );

             n->set_req(1,spill);

             must_recompute_live = true;

           }

         }

       }

       // Get value being defined

       uint lidx = _lrg_map.live_range_id(n);

       // Ignore the occasional brand-new live range

       if (lidx && lidx < _lrg_map.max_lrg_id()) {

         // Remove from live-out set

         liveout.remove(lidx);

         // Copies do not define a new value and so do not interfere.

         // Remove the copies source from the liveout set before interfering.

         uint idx = n->is_Copy();

         if (idx) {

           liveout.remove(_lrg_map.live_range_id(n->in(idx)));

         }

       }

       // Found a safepoint?

       JVMState *jvms = n->jvms();

       if( jvms ) {

         // Now scan for a live derived pointer

         IndexSetIterator elements(&liveout);

         uint neighbor;

         while ((neighbor = elements.next()) != 0) {

           // Find reaching DEF for base and derived values

           // This works because we are still in SSA during this call.

           Node *derived = lrgs(neighbor)._def;

           const TypePtr *tj = derived->bottom_type()->isa_ptr();

           assert(!derived->bottom_type()->isa_narrowoop() ||

                   derived->bottom_type()->make_ptr()->is_ptr()->_offset == 0, "sanity");

           // If its an OOP with a non-zero offset, then it is derived.

           if( tj && tj->_offset != 0 && tj->isa_oop_ptr() ) {

             Node *base = find_base_for_derived(derived_base_map, derived, maxlrg);

             assert(base->_idx < _lrg_map.size(), "");

             // Add reaching DEFs of derived pointer and base pointer as a

             // pair of inputs

             n->add_req(derived);

             n->add_req(base);

             // See if the base pointer is already live to this point.

             // Since I'm working on the SSA form, live-ness amounts to

             // reaching def's.  So if I find the base's live range then

             // I know the base's def reaches here.

             if ((_lrg_map.live_range_id(base) >= _lrg_map.max_lrg_id() || // (Brand new base (hence not live) or

                  !liveout.member(_lrg_map.live_range_id(base))) && // not live) AND

                  (_lrg_map.live_range_id(base) > 0) && // not a constant

                  _cfg._bbs[base->_idx] != b) { // base not def'd in blk)

               // Base pointer is not currently live.  Since I stretched

               // the base pointer to here and it crosses basic-block

               // boundaries, the global live info is now incorrect.

               // Recompute live.

               must_recompute_live = true;

             } // End of if base pointer is not live to debug info

           }

         } // End of scan all live data for derived ptrs crossing GC point

       } // End of if found a GC point

       // Make all inputs live

       if (!n->is_Phi()) {      // Phi function uses come from prior block

         for (uint k = 1; k < n->req(); k++) {

           uint lidx = _lrg_map.live_range_id(n->in(k));

           if (lidx < _lrg_map.max_lrg_id()) {

             liveout.insert(lidx);

           }

         }

       }

     } // End of forall instructions in block

     liveout.clear();  // Free the memory used by liveout.

   } // End of forall blocks

   _lrg_map.set_max_lrg_id(maxlrg);

   // If I created a new live range I need to recompute live

   if (maxlrg != _ifg->_maxlrg) {

     must_recompute_live = true;

   }

   return must_recompute_live != 0;

 }

 //------------------------------add_reference----------------------------------

 // Extend the node to LRG mapping

 void PhaseChaitin::add_reference(const Node *node, const Node *old_node) {

   _lrg_map.extend(node->_idx, _lrg_map.live_range_id(old_node));

 }

 //------------------------------dump-------------------------------------------

 #ifndef PRODUCT

 void PhaseChaitin::dump(const Node *n) const {

   uint r = (n->_idx < _lrg_map.size()) ? _lrg_map.find_const(n) : 0;

   tty->print("L%d",r);

   if (r && n->Opcode() != Op_Phi) {

     if( _node_regs ) {          // Got a post-allocation copy of allocation?

       tty->print("[");

       OptoReg::Name second = get_reg_second(n);

       if( OptoReg::is_valid(second) ) {

         if( OptoReg::is_reg(second) )

           tty->print("%s:",Matcher::regName[second]);

         else

           tty->print("%s+%d:",OptoReg::regname(OptoReg::c_frame_pointer), reg2offset_unchecked(second));

       }

       OptoReg::Name first = get_reg_first(n);

       if( OptoReg::is_reg(first) )

         tty->print("%s]",Matcher::regName[first]);

       else

          tty->print("%s+%d]",OptoReg::regname(OptoReg::c_frame_pointer), reg2offset_unchecked(first));

     } else

     n->out_RegMask().dump();

   }

   tty->print("/N%d\t",n->_idx);

   tty->print("%s === ", n->Name());

   uint k;

   for (k = 0; k < n->req(); k++) {

     Node *m = n->in(k);

     if (!m) {

       tty->print("_ ");

     }

     else {

       uint r = (m->_idx < _lrg_map.size()) ? _lrg_map.find_const(m) : 0;

       tty->print("L%d",r);

       // Data MultiNode's can have projections with no real registers.

       // Don't die while dumping them.

       int op = n->Opcode();

       if( r && op != Op_Phi && op != Op_Proj && op != Op_SCMemProj) {

         if( _node_regs ) {

           tty->print("[");

           OptoReg::Name second = get_reg_second(n->in(k));

           if( OptoReg::is_valid(second) ) {

             if( OptoReg::is_reg(second) )

               tty->print("%s:",Matcher::regName[second]);

             else

               tty->print("%s+%d:",OptoReg::regname(OptoReg::c_frame_pointer),

                          reg2offset_unchecked(second));

           }

           OptoReg::Name first = get_reg_first(n->in(k));

           if( OptoReg::is_reg(first) )

             tty->print("%s]",Matcher::regName[first]);

           else

             tty->print("%s+%d]",OptoReg::regname(OptoReg::c_frame_pointer),

                        reg2offset_unchecked(first));

         } else

           n->in_RegMask(k).dump();

       }

       tty->print("/N%d ",m->_idx);

     }

   }

   if( k < n->len() && n->in(k) ) tty->print("| ");

   for( ; k < n->len(); k++ ) {

     Node *m = n->in(k);

     if(!m) {

       break;

     }

     uint r = (m->_idx < _lrg_map.size()) ? _lrg_map.find_const(m) : 0;

     tty->print("L%d",r);

     tty->print("/N%d ",m->_idx);

   }

   if( n->is_Mach() ) n->as_Mach()->dump_spec(tty);

   else n->dump_spec(tty);

   if( _spilled_once.test(n->_idx ) ) {

     tty->print(" Spill_1");

     if( _spilled_twice.test(n->_idx ) )

       tty->print(" Spill_2");

   }

   tty->print("\n");

 }

 void PhaseChaitin::dump( const Block * b ) const {

   b->dump_head( &_cfg._bbs );

   // For all instructions

   for( uint j = 0; j < b->_nodes.size(); j++ )

     dump(b->_nodes[j]);

   // Print live-out info at end of block

   if( _live ) {

     tty->print("Liveout: ");

     IndexSet *live = _live->live(b);

     IndexSetIterator elements(live);

     tty->print("{");

     uint i;

     while ((i = elements.next()) != 0) {

       tty->print("L%d ", _lrg_map.find_const(i));

     }

     tty->print_cr("}");

   }

   tty->print("\n");

 }

 void PhaseChaitin::dump() const {

   tty->print( "--- Chaitin -- argsize: %d  framesize: %d ---\n",

               _matcher._new_SP, _framesize );

   // For all blocks

   for( uint i = 0; i < _cfg._num_blocks; i++ )

     dump(_cfg._blocks[i]);

   // End of per-block dump

   tty->print("\n");

   if (!_ifg) {

     tty->print("(No IFG.)\n");

     return;

   }

   // Dump LRG array

   tty->print("--- Live RanGe Array ---\n");

   for (uint i2 = 1; i2 < _lrg_map.max_lrg_id(); i2++) {

     tty->print("L%d: ",i2);

     if (i2 < _ifg->_maxlrg) {

       lrgs(i2).dump();

     }

     else {

       tty->print_cr("new LRG");

     }

   }

   tty->print_cr("");

   // Dump lo-degree list

   tty->print("Lo degree: ");

   for(uint i3 = _lo_degree; i3; i3 = lrgs(i3)._next )

     tty->print("L%d ",i3);

   tty->print_cr("");

   // Dump lo-stk-degree list

   tty->print("Lo stk degree: ");

   for(uint i4 = _lo_stk_degree; i4; i4 = lrgs(i4)._next )

     tty->print("L%d ",i4);

   tty->print_cr("");

   // Dump lo-degree list

   tty->print("Hi degree: ");

   for(uint i5 = _hi_degree; i5; i5 = lrgs(i5)._next )

     tty->print("L%d ",i5);

   tty->print_cr("");

 }

 //------------------------------dump_degree_lists------------------------------

 void PhaseChaitin::dump_degree_lists() const {

   // Dump lo-degree list

   tty->print("Lo degree: ");

   for( uint i = _lo_degree; i; i = lrgs(i)._next )

     tty->print("L%d ",i);

   tty->print_cr("");

   // Dump lo-stk-degree list

   tty->print("Lo stk degree: ");

   for(uint i2 = _lo_stk_degree; i2; i2 = lrgs(i2)._next )

     tty->print("L%d ",i2);

   tty->print_cr("");

   // Dump lo-degree list

   tty->print("Hi degree: ");

   for(uint i3 = _hi_degree; i3; i3 = lrgs(i3)._next )

     tty->print("L%d ",i3);

   tty->print_cr("");

 }

 //------------------------------dump_simplified--------------------------------

 void PhaseChaitin::dump_simplified() const {

   tty->print("Simplified: ");

   for( uint i = _simplified; i; i = lrgs(i)._next )

     tty->print("L%d ",i);

   tty->print_cr("");

 }

 static char *print_reg( OptoReg::Name reg, const PhaseChaitin *pc, char *buf ) {

   if ((int)reg < 0)

     sprintf(buf, "<OptoReg::%d>", (int)reg);

   else if (OptoReg::is_reg(reg))

     strcpy(buf, Matcher::regName[reg]);

   else

     sprintf(buf,"%s + #%d",OptoReg::regname(OptoReg::c_frame_pointer),

             pc->reg2offset(reg));

   return buf+strlen(buf);

 }

 //------------------------------dump_register----------------------------------

 // Dump a register name into a buffer.  Be intelligent if we get called

 // before allocation is complete.

 char *PhaseChaitin::dump_register( const Node *n, char *buf  ) const {

   if( !this ) {                 // Not got anything?

     sprintf(buf,"N%d",n->_idx); // Then use Node index

   } else if( _node_regs ) {

     // Post allocation, use direct mappings, no LRG info available

     print_reg( get_reg_first(n), this, buf );

   } else {

     uint lidx = _lrg_map.find_const(n); // Grab LRG number

     if( !_ifg ) {

       sprintf(buf,"L%d",lidx);  // No register binding yet

     } else if( !lidx ) {        // Special, not allocated value

       strcpy(buf,"Special");

     } else {

       if (lrgs(lidx)._is_vector) {

         if (lrgs(lidx).mask().is_bound_set(lrgs(lidx).num_regs()))

           print_reg( lrgs(lidx).reg(), this, buf ); // a bound machine register

         else

           sprintf(buf,"L%d",lidx); // No register binding yet

       } else if( (lrgs(lidx).num_regs() == 1)

                  ? lrgs(lidx).mask().is_bound1()

                  : lrgs(lidx).mask().is_bound_pair() ) {

         // Hah!  We have a bound machine register

         print_reg( lrgs(lidx).reg(), this, buf );

       } else {

         sprintf(buf,"L%d",lidx); // No register binding yet

       }

     }

   }

   return buf+strlen(buf);

 }

 //----------------------dump_for_spill_split_recycle--------------------------

 void PhaseChaitin::dump_for_spill_split_recycle() const {

   if( WizardMode && (PrintCompilation || PrintOpto) ) {

     // Display which live ranges need to be split and the allocator's state

     tty->print_cr("Graph-Coloring Iteration %d will split the following live ranges", _trip_cnt);

     for (uint bidx = 1; bidx < _lrg_map.max_lrg_id(); bidx++) {

       if( lrgs(bidx).alive() && lrgs(bidx).reg() >= LRG::SPILL_REG ) {

         tty->print("L%d: ", bidx);

         lrgs(bidx).dump();

       }

     }

     tty->cr();

     dump();

   }

 }

 //------------------------------dump_frame------------------------------------

 void PhaseChaitin::dump_frame() const {

   const char *fp = OptoReg::regname(OptoReg::c_frame_pointer);

   const TypeTuple *domain = C->tf()->domain();

   const int        argcnt = domain->cnt() - TypeFunc::Parms;

   // Incoming arguments in registers dump

   for( int k = 0; k < argcnt; k++ ) {

     OptoReg::Name parmreg = _matcher._parm_regs[k].first();

     if( OptoReg::is_reg(parmreg))  {

       const char *reg_name = OptoReg::regname(parmreg);

       tty->print("#r%3.3d %s", parmreg, reg_name);

       parmreg = _matcher._parm_regs[k].second();

       if( OptoReg::is_reg(parmreg))  {

         tty->print(":%s", OptoReg::regname(parmreg));

       }

       tty->print("   : parm %d: ", k);

       domain->field_at(k + TypeFunc::Parms)->dump();

       tty->print_cr("");

     }

   }

   // Check for un-owned padding above incoming args

   OptoReg::Name reg = _matcher._new_SP;

   if( reg > _matcher._in_arg_limit ) {

     reg = OptoReg::add(reg, -1);

     tty->print_cr("#r%3.3d %s+%2d: pad0, owned by CALLER", reg, fp, reg2offset_unchecked(reg));

   }

   // Incoming argument area dump

   OptoReg::Name begin_in_arg = OptoReg::add(_matcher._old_SP,C->out_preserve_stack_slots());

   while( reg > begin_in_arg ) {

     reg = OptoReg::add(reg, -1);

     tty->print("#r%3.3d %s+%2d: ",reg,fp,reg2offset_unchecked(reg));

     int j;

     for( j = 0; j < argcnt; j++) {

       if( _matcher._parm_regs[j].first() == reg ||

           _matcher._parm_regs[j].second() == reg ) {

         tty->print("parm %d: ",j);

         domain->field_at(j + TypeFunc::Parms)->dump();

         tty->print_cr("");

         break;

       }

     }

     if( j >= argcnt )

       tty->print_cr("HOLE, owned by SELF");

   }

   // Old outgoing preserve area

   while( reg > _matcher._old_SP ) {

     reg = OptoReg::add(reg, -1);

     tty->print_cr("#r%3.3d %s+%2d: old out preserve",reg,fp,reg2offset_unchecked(reg));

   }

   // Old SP

   tty->print_cr("# -- Old %s -- Framesize: %d --",fp,

     reg2offset_unchecked(OptoReg::add(_matcher._old_SP,-1)) - reg2offset_unchecked(_matcher._new_SP)+jintSize);

   // Preserve area dump

   int fixed_slots = C->fixed_slots();

   OptoReg::Name begin_in_preserve = OptoReg::add(_matcher._old_SP, -(int)C->in_preserve_stack_slots());

   OptoReg::Name return_addr = _matcher.return_addr();

   reg = OptoReg::add(reg, -1);

   while (OptoReg::is_stack(reg)) {

     tty->print("#r%3.3d %s+%2d: ",reg,fp,reg2offset_unchecked(reg));

     if (return_addr == reg) {

       tty->print_cr("return address");

     } else if (reg >= begin_in_preserve) {

       // Preserved slots are present on x86

       if (return_addr == OptoReg::add(reg, VMRegImpl::slots_per_word))

         tty->print_cr("saved fp register");

       else if (return_addr == OptoReg::add(reg, 2*VMRegImpl::slots_per_word) &&

                VerifyStackAtCalls)

         tty->print_cr("0xBADB100D   +VerifyStackAtCalls");

       else

         tty->print_cr("in_preserve");

     } else if ((int)OptoReg::reg2stack(reg) < fixed_slots) {

       tty->print_cr("Fixed slot %d", OptoReg::reg2stack(reg));

     } else {

       tty->print_cr("pad2, stack alignment");

     }

     reg = OptoReg::add(reg, -1);

   }

   // Spill area dump

   reg = OptoReg::add(_matcher._new_SP, _framesize );

   while( reg > _matcher._out_arg_limit ) {

     reg = OptoReg::add(reg, -1);

     tty->print_cr("#r%3.3d %s+%2d: spill",reg,fp,reg2offset_unchecked(reg));

   }

   // Outgoing argument area dump

   while( reg > OptoReg::add(_matcher._new_SP, C->out_preserve_stack_slots()) ) {

     reg = OptoReg::add(reg, -1);

     tty->print_cr("#r%3.3d %s+%2d: outgoing argument",reg,fp,reg2offset_unchecked(reg));

   }

   // Outgoing new preserve area

   while( reg > _matcher._new_SP ) {

     reg = OptoReg::add(reg, -1);

     tty->print_cr("#r%3.3d %s+%2d: new out preserve",reg,fp,reg2offset_unchecked(reg));

   }

   tty->print_cr("#");

 }

 //------------------------------dump_bb----------------------------------------

 void PhaseChaitin::dump_bb( uint pre_order ) const {

   tty->print_cr("---dump of B%d---",pre_order);

   for( uint i = 0; i < _cfg._num_blocks; i++ ) {

     Block *b = _cfg._blocks[i];

     if( b->_pre_order == pre_order )

       dump(b);

   }

 }

 //------------------------------dump_lrg---------------------------------------

 void PhaseChaitin::dump_lrg( uint lidx, bool defs_only ) const {

   tty->print_cr("---dump of L%d---",lidx);

   if (_ifg) {

     if (lidx >= _lrg_map.max_lrg_id()) {

       tty->print("Attempt to print live range index beyond max live range.\n");

       return;

     }

     tty->print("L%d: ",lidx);

     if (lidx < _ifg->_maxlrg) {

       lrgs(lidx).dump();

     } else {

       tty->print_cr("new LRG");

     }

   }

   if( _ifg && lidx < _ifg->_maxlrg) {

     tty->print("Neighbors: %d - ", _ifg->neighbor_cnt(lidx));

     _ifg->neighbors(lidx)->dump();

     tty->cr();

   }

   // For all blocks

   for( uint i = 0; i < _cfg._num_blocks; i++ ) {

     Block *b = _cfg._blocks[i];

     int dump_once = 0;

     // For all instructions

     for( uint j = 0; j < b->_nodes.size(); j++ ) {

       Node *n = b->_nodes[j];

       if (_lrg_map.find_const(n) == lidx) {

         if (!dump_once++) {

           tty->cr();

           b->dump_head( &_cfg._bbs );

         }

         dump(n);

         continue;

       }

       if (!defs_only) {

         uint cnt = n->req();

         for( uint k = 1; k < cnt; k++ ) {

           Node *m = n->in(k);

           if (!m)  {

             continue;  // be robust in the dumper

           }

           if (_lrg_map.find_const(m) == lidx) {

             if (!dump_once++) {

               tty->cr();

               b->dump_head(&_cfg._bbs);

             }

             dump(n);

           }

         }

       }

     }

   } // End of per-block dump

   tty->cr();

 }

 #endif // not PRODUCT

 //------------------------------print_chaitin_statistics-------------------------------

 int PhaseChaitin::_final_loads  = 0;

 int PhaseChaitin::_final_stores = 0;

 int PhaseChaitin::_final_memoves= 0;

 int PhaseChaitin::_final_copies = 0;

 double PhaseChaitin::_final_load_cost  = 0;

 double PhaseChaitin::_final_store_cost = 0;

 double PhaseChaitin::_final_memove_cost= 0;

 double PhaseChaitin::_final_copy_cost  = 0;

 int PhaseChaitin::_conserv_coalesce = 0;

 int PhaseChaitin::_conserv_coalesce_pair = 0;

 int PhaseChaitin::_conserv_coalesce_trie = 0;

 int PhaseChaitin::_conserv_coalesce_quad = 0;

 int PhaseChaitin::_post_alloc = 0;

 int PhaseChaitin::_lost_opp_pp_coalesce = 0;

 int PhaseChaitin::_lost_opp_cflow_coalesce = 0;

 int PhaseChaitin::_used_cisc_instructions   = 0;

 int PhaseChaitin::_unused_cisc_instructions = 0;

 int PhaseChaitin::_allocator_attempts       = 0;

 int PhaseChaitin::_allocator_successes      = 0;

 #ifndef PRODUCT

 uint PhaseChaitin::_high_pressure           = 0;

 uint PhaseChaitin::_low_pressure            = 0;

 void PhaseChaitin::print_chaitin_statistics() {

   tty->print_cr("Inserted %d spill loads, %d spill stores, %d mem-mem moves and %d copies.", _final_loads, _final_stores, _final_memoves, _final_copies);

   tty->print_cr("Total load cost= %6.0f, store cost = %6.0f, mem-mem cost = %5.2f, copy cost = %5.0f.", _final_load_cost, _final_store_cost, _final_memove_cost, _final_copy_cost);

   tty->print_cr("Adjusted spill cost = %7.0f.",

                 _final_load_cost*4.0 + _final_store_cost  * 2.0 +

                 _final_copy_cost*1.0 + _final_memove_cost*12.0);

   tty->print("Conservatively coalesced %d copies, %d pairs",

                 _conserv_coalesce, _conserv_coalesce_pair);

   if( _conserv_coalesce_trie || _conserv_coalesce_quad )

     tty->print(", %d tries, %d quads", _conserv_coalesce_trie, _conserv_coalesce_quad);

   tty->print_cr(", %d post alloc.", _post_alloc);

   if( _lost_opp_pp_coalesce || _lost_opp_cflow_coalesce )

     tty->print_cr("Lost coalesce opportunity, %d private-private, and %d cflow interfered.",

                   _lost_opp_pp_coalesce, _lost_opp_cflow_coalesce );

   if( _used_cisc_instructions || _unused_cisc_instructions )

     tty->print_cr("Used cisc instruction  %d,  remained in register %d",

                    _used_cisc_instructions, _unused_cisc_instructions);

   if( _allocator_successes != 0 )

     tty->print_cr("Average allocation trips %f", (float)_allocator_attempts/(float)_allocator_successes);

   tty->print_cr("High Pressure Blocks = %d, Low Pressure Blocks = %d", _high_pressure, _low_pressure);

 }

 #endif // not PRODUCT