Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2000-2006 Sun Microsystems, Inc.  All Rights Reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

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  */

 #include "incls/_precompiled.incl"

 #include "incls/_reg_split.cpp.incl"

 //------------------------------Split--------------------------------------

 // Walk the graph in RPO and for each lrg which spills, propogate reaching

 // definitions.  During propogation, split the live range around regions of

 // High Register Pressure (HRP).  If a Def is in a region of Low Register

 // Pressure (LRP), it will not get spilled until we encounter a region of

 // HRP between it and one of its uses.  We will spill at the transition

 // point between LRP and HRP.  Uses in the HRP region will use the spilled

 // Def.  The first Use outside the HRP region will generate a SpillCopy to

 // hoist the live range back up into a register, and all subsequent uses

 // will use that new Def until another HRP region is encountered.  Defs in

 // HRP regions will get trailing SpillCopies to push the LRG down into the

 // stack immediately.

 //

 // As a side effect, unlink from (hence make dead) coalesced copies.

 //

 static const char out_of_nodes[] = "out of nodes during split";

 //------------------------------get_spillcopy_wide-----------------------------

 // Get a SpillCopy node with wide-enough masks.  Use the 'wide-mask', the

 // wide ideal-register spill-mask if possible.  If the 'wide-mask' does

 // not cover the input (or output), use the input (or output) mask instead.

 Node *PhaseChaitin::get_spillcopy_wide( Node *def, Node *use, uint uidx ) {

   // If ideal reg doesn't exist we've got a bad schedule happening

   // that is forcing us to spill something that isn't spillable.

   // Bail rather than abort

   int ireg = def->ideal_reg();

   if( ireg == 0 || ireg == Op_RegFlags ) {

     C->record_method_not_compilable("attempted to spill a non-spillable item");

     return NULL;

   }

   if (C->check_node_count(NodeLimitFudgeFactor, out_of_nodes)) {

     return NULL;

   }

   const RegMask *i_mask = &def->out_RegMask();

   const RegMask *w_mask = C->matcher()->idealreg2spillmask[ireg];

   const RegMask *o_mask = use ? &use->in_RegMask(uidx) : w_mask;

   const RegMask *w_i_mask = w_mask->overlap( *i_mask ) ? w_mask : i_mask;

   const RegMask *w_o_mask;

   if( w_mask->overlap( *o_mask ) && // Overlap AND

       ((ireg != Op_RegL && ireg != Op_RegD // Single use or aligned

 #ifdef _LP64

         && ireg != Op_RegP

 #endif

          ) || o_mask->is_aligned_Pairs()) ) {

     // Don't come here for mis-aligned doubles

     w_o_mask = w_mask;

   } else {                      // wide ideal mask does not overlap with o_mask

     // Mis-aligned doubles come here and XMM->FPR moves on x86.

     w_o_mask = o_mask;          // Must target desired registers

     // Does the ideal-reg-mask overlap with o_mask?  I.e., can I use

     // a reg-reg move or do I need a trip across register classes

     // (and thus through memory)?

     if( !C->matcher()->idealreg2regmask[ireg]->overlap( *o_mask) && o_mask->is_UP() )

       // Here we assume a trip through memory is required.

       w_i_mask = &C->FIRST_STACK_mask();

   }

   return new (C) MachSpillCopyNode( def, *w_i_mask, *w_o_mask );

 }

 //------------------------------insert_proj------------------------------------

 // Insert the spill at chosen location.  Skip over any interveneing Proj's or

 // Phis.  Skip over a CatchNode and projs, inserting in the fall-through block

 // instead.  Update high-pressure indices.  Create a new live range.

 void PhaseChaitin::insert_proj( Block *b, uint i, Node *spill, uint maxlrg ) {

   // Skip intervening ProjNodes.  Do not insert between a ProjNode and

   // its definer.

   while( i < b->_nodes.size() &&

          (b->_nodes[i]->is_Proj() ||

           b->_nodes[i]->is_Phi() ) )

     i++;

   // Do not insert between a call and his Catch

   if( b->_nodes[i]->is_Catch() ) {

     // Put the instruction at the top of the fall-thru block.

     // Find the fall-thru projection

     while( 1 ) {

       const CatchProjNode *cp = b->_nodes[++i]->as_CatchProj();

       if( cp->_con == CatchProjNode::fall_through_index )

         break;

     }

     int sidx = i - b->end_idx()-1;

     b = b->_succs[sidx];        // Switch to successor block

     i = 1;                      // Right at start of block

   }

   b->_nodes.insert(i,spill);    // Insert node in block

   _cfg._bbs.map(spill->_idx,b); // Update node->block mapping to reflect

   // Adjust the point where we go hi-pressure

   if( i <= b->_ihrp_index ) b->_ihrp_index++;

   if( i <= b->_fhrp_index ) b->_fhrp_index++;

   // Assign a new Live Range Number to the SpillCopy and grow

   // the node->live range mapping.

   new_lrg(spill,maxlrg);

 }

 //------------------------------split_DEF--------------------------------------

 // There are four catagories of Split; UP/DOWN x DEF/USE

 // Only three of these really occur as DOWN/USE will always color

 // Any Split with a DEF cannot CISC-Spill now.  Thus we need

 // two helper routines, one for Split DEFS (insert after instruction),

 // one for Split USES (insert before instruction).  DEF insertion

 // happens inside Split, where the Leaveblock array is updated.

 uint PhaseChaitin::split_DEF( Node *def, Block *b, int loc, uint maxlrg, Node **Reachblock, Node **debug_defs, GrowableArray<uint> splits, int slidx ) {

 #ifdef ASSERT

   // Increment the counter for this lrg

   splits.at_put(slidx, splits.at(slidx)+1);

 #endif

   // If we are spilling the memory op for an implicit null check, at the

   // null check location (ie - null check is in HRP block) we need to do

   // the null-check first, then spill-down in the following block.

   // (The implicit_null_check function ensures the use is also dominated

   // by the branch-not-taken block.)

   Node *be = b->end();

   if( be->is_MachNullCheck() && be->in(1) == def && def == b->_nodes[loc] ) {

     // Spill goes in the branch-not-taken block

     b = b->_succs[b->_nodes[b->end_idx()+1]->Opcode() == Op_IfTrue];

     loc = 0;                    // Just past the Region

   }

   assert( loc >= 0, "must insert past block head" );

   // Get a def-side SpillCopy

   Node *spill = get_spillcopy_wide(def,NULL,0);

   // Did we fail to split?, then bail

   if (!spill) {

     return 0;

   }

   // Insert the spill at chosen location

   insert_proj( b, loc+1, spill, maxlrg++);

   // Insert new node into Reaches array

   Reachblock[slidx] = spill;

   // Update debug list of reaching down definitions by adding this one

   debug_defs[slidx] = spill;

   // return updated count of live ranges

   return maxlrg;

 }

 //------------------------------split_USE--------------------------------------

 // Splits at uses can involve redeffing the LRG, so no CISC Spilling there.

 // Debug uses want to know if def is already stack enabled.

 uint PhaseChaitin::split_USE( Node *def, Block *b, Node *use, uint useidx, uint maxlrg, bool def_down, bool cisc_sp, GrowableArray<uint> splits, int slidx ) {

 #ifdef ASSERT

   // Increment the counter for this lrg

   splits.at_put(slidx, splits.at(slidx)+1);

 #endif

   // Some setup stuff for handling debug node uses

   JVMState* jvms = use->jvms();

   uint debug_start = jvms ? jvms->debug_start() : 999999;

   uint debug_end   = jvms ? jvms->debug_end()   : 999999;

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

   // Check for use of debug info

   if (useidx >= debug_start && useidx < debug_end) {

     // Actually it's perfectly legal for constant debug info to appear

     // just unlikely.  In this case the optimizer left a ConI of a 4

     // as both inputs to a Phi with only a debug use.  It's a single-def

     // live range of a rematerializable value.  The live range spills,

     // rematerializes and now the ConI directly feeds into the debug info.

     // assert(!def->is_Con(), "constant debug info already constructed directly");

     // Special split handling for Debug Info

     // If DEF is DOWN, just hook the edge and return

     // If DEF is UP, Split it DOWN for this USE.

     if( def->is_Mach() ) {

       if( def_down ) {

         // DEF is DOWN, so connect USE directly to the DEF

         use->set_req(useidx, def);

       } else {

         // Block and index where the use occurs.

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

         // Put the clone just prior to use

         int bindex = b->find_node(use);

         // DEF is UP, so must copy it DOWN and hook in USE

         // Insert SpillCopy before the USE, which uses DEF as its input,

         // and defs a new live range, which is used by this node.

         Node *spill = get_spillcopy_wide(def,use,useidx);

         // did we fail to split?

         if (!spill) {

           // Bail

           return 0;

         }

         // insert into basic block

         insert_proj( b, bindex, spill, maxlrg++ );

         // Use the new split

         use->set_req(useidx,spill);

       }

       // No further split handling needed for this use

       return maxlrg;

     }  // End special splitting for debug info live range

   }  // If debug info

   // CISC-SPILLING

   // Finally, check to see if USE is CISC-Spillable, and if so,

   // gather_lrg_masks will add the flags bit to its mask, and

   // no use side copy is needed.  This frees up the live range

   // register choices without causing copy coalescing, etc.

   if( UseCISCSpill && cisc_sp ) {

     int inp = use->cisc_operand();

     if( inp != AdlcVMDeps::Not_cisc_spillable )

       // Convert operand number to edge index number

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

     if( inp == (int)useidx ) {

       use->set_req(useidx, def);

 #ifndef PRODUCT

       if( TraceCISCSpill ) {

         tty->print("  set_split: ");

         use->dump();

       }

 #endif

       return maxlrg;

     }

   }

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

   // Insert a Copy before the use

   // Block and index where the use occurs.

   int bindex;

   // Phi input spill-copys belong at the end of the prior block

   if( use->is_Phi() ) {

     b = _cfg._bbs[b->pred(useidx)->_idx];

     bindex = b->end_idx();

   } else {

     // Put the clone just prior to use

     bindex = b->find_node(use);

   }

   Node *spill = get_spillcopy_wide( def, use, useidx );

   if( !spill ) return 0;        // Bailed out

   // Insert SpillCopy before the USE, which uses the reaching DEF as

   // its input, and defs a new live range, which is used by this node.

   insert_proj( b, bindex, spill, maxlrg++ );

   // Use the spill/clone

   use->set_req(useidx,spill);

   // return updated live range count

   return maxlrg;

 }

 //------------------------------split_Rematerialize----------------------------

 // Clone a local copy of the def.

 Node *PhaseChaitin::split_Rematerialize( Node *def, Block *b, uint insidx, uint &maxlrg, GrowableArray<uint> splits, int slidx, uint *lrg2reach, Node **Reachblock, bool walkThru ) {

   // The input live ranges will be stretched to the site of the new

   // instruction.  They might be stretched past a def and will thus

   // have the old and new values of the same live range alive at the

   // same time - a definite no-no.  Split out private copies of

   // the inputs.

   if( def->req() > 1 ) {

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

       Node *in = def->in(i);

       // Check for single-def (LRG cannot redefined)

       uint lidx = n2lidx(in);

       if( lidx >= _maxlrg ) continue; // Value is a recent spill-copy

       if (lrgs(lidx).is_singledef()) continue;

       Block *b_def = _cfg._bbs[def->_idx];

       int idx_def = b_def->find_node(def);

       Node *in_spill = get_spillcopy_wide( in, def, i );

       if( !in_spill ) return 0; // Bailed out

       insert_proj(b_def,idx_def,in_spill,maxlrg++);

       if( b_def == b )

         insidx++;

       def->set_req(i,in_spill);

     }

   }

   Node *spill = def->clone();

   if (C->check_node_count(NodeLimitFudgeFactor, out_of_nodes)) {

     // Check when generating nodes

     return 0;

   }

   // See if any inputs are currently being spilled, and take the

   // latest copy of spilled inputs.

   if( spill->req() > 1 ) {

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

       Node *in = spill->in(i);

       uint lidx = Find_id(in);

       // Walk backwards thru spill copy node intermediates

       if (walkThru) {

         while ( in->is_SpillCopy() && lidx >= _maxlrg ) {

           in = in->in(1);

           lidx = Find_id(in);

         }

         if (lidx < _maxlrg && lrgs(lidx).is_multidef()) {

           // walkThru found a multidef LRG, which is unsafe to use, so

           // just keep the original def used in the clone.

           in = spill->in(i);

           lidx = Find_id(in);

         }

       }

       if( lidx < _maxlrg && lrgs(lidx).reg() >= LRG::SPILL_REG ) {

         Node *rdef = Reachblock[lrg2reach[lidx]];

         if( rdef ) spill->set_req(i,rdef);

       }

     }

   }

   assert( spill->out_RegMask().is_UP(), "rematerialize to a reg" );

   // Rematerialized op is def->spilled+1

   set_was_spilled(spill);

   if( _spilled_once.test(def->_idx) )

     set_was_spilled(spill);

   insert_proj( b, insidx, spill, maxlrg++ );

 #ifdef ASSERT

   // Increment the counter for this lrg

   splits.at_put(slidx, splits.at(slidx)+1);

 #endif

   // See if the cloned def kills any flags, and copy those kills as well

   uint i = insidx+1;

   if( clone_projs( b, i, def, spill, maxlrg ) ) {

     // Adjust the point where we go hi-pressure

     if( i <= b->_ihrp_index ) b->_ihrp_index++;

     if( i <= b->_fhrp_index ) b->_fhrp_index++;

   }

   return spill;

 }

 //------------------------------is_high_pressure-------------------------------

 // Function to compute whether or not this live range is "high pressure"

 // in this block - whether it spills eagerly or not.

 bool PhaseChaitin::is_high_pressure( Block *b, LRG *lrg, uint insidx ) {

   if( lrg->_was_spilled1 ) return true;

   // Forced spilling due to conflict?  Then split only at binding uses

   // or defs, not for supposed capacity problems.

   // CNC - Turned off 7/8/99, causes too much spilling

   // if( lrg->_is_bound ) return false;

   // Not yet reached the high-pressure cutoff point, so low pressure

   uint hrp_idx = lrg->_is_float ? b->_fhrp_index : b->_ihrp_index;

   if( insidx < hrp_idx ) return false;

   // Register pressure for the block as a whole depends on reg class

   int block_pres = lrg->_is_float ? b->_freg_pressure : b->_reg_pressure;

   // Bound live ranges will split at the binding points first;

   // Intermediate splits should assume the live range's register set

   // got "freed up" and that num_regs will become INT_PRESSURE.

   int bound_pres = lrg->_is_float ? FLOATPRESSURE : INTPRESSURE;

   // Effective register pressure limit.

   int lrg_pres = (lrg->get_invalid_mask_size() > lrg->num_regs())

     ? (lrg->get_invalid_mask_size() >> (lrg->num_regs()-1)) : bound_pres;

   // High pressure if block pressure requires more register freedom

   // than live range has.

   return block_pres >= lrg_pres;

 }

 //------------------------------prompt_use---------------------------------

 // True if lidx is used before any real register is def'd in the block

 bool PhaseChaitin::prompt_use( Block *b, uint lidx ) {

   if( lrgs(lidx)._was_spilled2 ) return false;

   // Scan block for 1st use.

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

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

     // Ignore PHI use, these can be up or down

     if( n->is_Phi() ) continue;

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

       if( Find_id(n->in(j)) == lidx )

         return true;          // Found 1st use!

     if( n->out_RegMask().is_NotEmpty() ) return false;

   }

   return false;

 }

 //------------------------------Split--------------------------------------

 //----------Split Routine----------

 // ***** NEW SPLITTING HEURISTIC *****

 // DEFS: If the DEF is in a High Register Pressure(HRP) Block, split there.

 //        Else, no split unless there is a HRP block between a DEF and

 //        one of its uses, and then split at the HRP block.

 //

 // USES: If USE is in HRP, split at use to leave main LRG on stack.

 //       Else, hoist LRG back up to register only (ie - split is also DEF)

 // We will compute a new maxlrg as we go

 uint PhaseChaitin::Split( uint maxlrg ) {

   NOT_PRODUCT( Compile::TracePhase t3("regAllocSplit", &_t_regAllocSplit, TimeCompiler); )

   uint                 bidx, pidx, slidx, insidx, inpidx, twoidx;

   uint                 non_phi = 1, spill_cnt = 0;

   Node               **Reachblock;

   Node                *n1, *n2, *n3;

   Node_List           *defs,*phis;

   bool                *UPblock;

   bool                 u1, u2, u3;

   Block               *b, *pred;

   PhiNode             *phi;

   GrowableArray<uint>  lidxs;

   // Array of counters to count splits per live range

   GrowableArray<uint>  splits;

   //----------Setup Code----------

   // Create a convenient mapping from lrg numbers to reaches/leaves indices

   uint *lrg2reach = NEW_RESOURCE_ARRAY( uint, _maxlrg );

   // Keep track of DEFS & Phis for later passes

   defs = new Node_List();

   phis = new Node_List();

   // Gather info on which LRG's are spilling, and build maps

   for( bidx = 1; bidx < _maxlrg; bidx++ ) {

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

       assert(!lrgs(bidx).mask().is_AllStack(),"AllStack should color");

       lrg2reach[bidx] = spill_cnt;

       spill_cnt++;

       lidxs.append(bidx);

 #ifdef ASSERT

       // Initialize the split counts to zero

       splits.append(0);

 #endif

 #ifndef PRODUCT

       if( PrintOpto && WizardMode && lrgs(bidx)._was_spilled1 )

         tty->print_cr("Warning, 2nd spill of L%d",bidx);

 #endif

     }

   }

   // Create side arrays for propagating reaching defs info.

   // Each block needs a node pointer for each spilling live range for the

   // Def which is live into the block.  Phi nodes handle multiple input

   // Defs by querying the output of their predecessor blocks and resolving

   // them to a single Def at the phi.  The pointer is updated for each

   // Def in the block, and then becomes the output for the block when

   // processing of the block is complete.  We also need to track whether

   // a Def is UP or DOWN.  UP means that it should get a register (ie -

   // it is always in LRP regions), and DOWN means that it is probably

   // on the stack (ie - it crosses HRP regions).

   Node ***Reaches     = NEW_RESOURCE_ARRAY( Node**, _cfg._num_blocks+1 );

   bool  **UP          = NEW_RESOURCE_ARRAY( bool*, _cfg._num_blocks+1 );

   Node  **debug_defs  = NEW_RESOURCE_ARRAY( Node*, spill_cnt );

   VectorSet **UP_entry= NEW_RESOURCE_ARRAY( VectorSet*, spill_cnt );

   // Initialize Reaches & UP

   for( bidx = 0; bidx < _cfg._num_blocks+1; bidx++ ) {

     Reaches[bidx]     = NEW_RESOURCE_ARRAY( Node*, spill_cnt );

     UP[bidx]          = NEW_RESOURCE_ARRAY( bool, spill_cnt );

     Node **Reachblock = Reaches[bidx];

     bool *UPblock     = UP[bidx];

     for( slidx = 0; slidx < spill_cnt; slidx++ ) {

       UPblock[slidx] = true;     // Assume they start in registers

       Reachblock[slidx] = NULL;  // Assume that no def is present

     }

   }

   // Initialize to array of empty vectorsets

   for( slidx = 0; slidx < spill_cnt; slidx++ )

     UP_entry[slidx] = new VectorSet(Thread::current()->resource_area());

   //----------PASS 1----------

   //----------Propagation & Node Insertion Code----------

   // Walk the Blocks in RPO for DEF & USE info

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

     if (C->check_node_count(spill_cnt, out_of_nodes)) {

       return 0;

     }

     b  = _cfg._blocks[bidx];

     // Reaches & UP arrays for this block

     Reachblock = Reaches[b->_pre_order];

     UPblock    = UP[b->_pre_order];

     // Reset counter of start of non-Phi nodes in block

     non_phi = 1;

     //----------Block Entry Handling----------

     // Check for need to insert a new phi

     // Cycle through this block's predecessors, collecting Reaches

     // info for each spilled LRG.  If they are identical, no phi is

     // needed.  If they differ, check for a phi, and insert if missing,

     // or update edges if present.  Set current block's Reaches set to

     // be either the phi's or the reaching def, as appropriate.

     // If no Phi is needed, check if the LRG needs to spill on entry

     // to the block due to HRP.

     for( slidx = 0; slidx < spill_cnt; slidx++ ) {

       // Grab the live range number

       uint lidx = lidxs.at(slidx);

       // Do not bother splitting or putting in Phis for single-def

       // rematerialized live ranges.  This happens alot to constants

       // with long live ranges.

       if( lrgs(lidx).is_singledef() &&

           lrgs(lidx)._def->rematerialize() ) {

         // reset the Reaches & UP entries

         Reachblock[slidx] = lrgs(lidx)._def;

         UPblock[slidx] = true;

         // Record following instruction in case 'n' rematerializes and

         // kills flags

         Block *pred1 = _cfg._bbs[b->pred(1)->_idx];

         continue;

       }

       // Initialize needs_phi and needs_split

       bool needs_phi = false;

       bool needs_split = false;

       bool has_phi = false;

       // Walk the predecessor blocks to check inputs for that live range

       // Grab predecessor block header

       n1 = b->pred(1);

       // Grab the appropriate reaching def info for inpidx

       pred = _cfg._bbs[n1->_idx];

       pidx = pred->_pre_order;

       Node **Ltmp = Reaches[pidx];

       bool  *Utmp = UP[pidx];

       n1 = Ltmp[slidx];

       u1 = Utmp[slidx];

       // Initialize node for saving type info

       n3 = n1;

       u3 = u1;

       // Compare inputs to see if a Phi is needed

       for( inpidx = 2; inpidx < b->num_preds(); inpidx++ ) {

         // Grab predecessor block headers

         n2 = b->pred(inpidx);

         // Grab the appropriate reaching def info for inpidx

         pred = _cfg._bbs[n2->_idx];

         pidx = pred->_pre_order;

         Ltmp = Reaches[pidx];

         Utmp = UP[pidx];

         n2 = Ltmp[slidx];

         u2 = Utmp[slidx];

         // For each LRG, decide if a phi is necessary

         if( n1 != n2 ) {

           needs_phi = true;

         }

         // See if the phi has mismatched inputs, UP vs. DOWN

         if( n1 && n2 && (u1 != u2) ) {

           needs_split = true;

         }

         // Move n2/u2 to n1/u1 for next iteration

         n1 = n2;

         u1 = u2;

         // Preserve a non-NULL predecessor for later type referencing

         if( (n3 == NULL) && (n2 != NULL) ){

           n3 = n2;

           u3 = u2;

         }

       }  // End for all potential Phi inputs

       // check block for appropriate phinode & update edges

       for( insidx = 1; insidx <= b->end_idx(); insidx++ ) {

         n1 = b->_nodes[insidx];

         // bail if this is not a phi

         phi = n1->is_Phi() ? n1->as_Phi() : NULL;

         if( phi == NULL ) {

           // Keep track of index of first non-PhiNode instruction in block

           non_phi = insidx;

           // break out of the for loop as we have handled all phi nodes

           break;

         }

         // must be looking at a phi

         if( Find_id(n1) == lidxs.at(slidx) ) {

           // found the necessary phi

           needs_phi = false;

           has_phi = true;

           // initialize the Reaches entry for this LRG

           Reachblock[slidx] = phi;

           break;

         }  // end if found correct phi

       }  // end for all phi's

       // If a phi is needed or exist, check for it

       if( needs_phi || has_phi ) {

         // add new phinode if one not already found

         if( needs_phi ) {

           // create a new phi node and insert it into the block

           // type is taken from left over pointer to a predecessor

           assert(n3,"No non-NULL reaching DEF for a Phi");

           phi = new (C, b->num_preds()) PhiNode(b->head(), n3->bottom_type());

           // initialize the Reaches entry for this LRG

           Reachblock[slidx] = phi;

           // add node to block & node_to_block mapping

           insert_proj( b, insidx++, phi, maxlrg++ );

           non_phi++;

           // Reset new phi's mapping to be the spilling live range

           _names.map(phi->_idx, lidx);

           assert(Find_id(phi) == lidx,"Bad update on Union-Find mapping");

         }  // end if not found correct phi

         // Here you have either found or created the Phi, so record it

         assert(phi != NULL,"Must have a Phi Node here");

         phis->push(phi);

         // PhiNodes should either force the LRG UP or DOWN depending

         // on its inputs and the register pressure in the Phi's block.

         UPblock[slidx] = true;  // Assume new DEF is UP

         // If entering a high-pressure area with no immediate use,

         // assume Phi is DOWN

         if( is_high_pressure( b, &lrgs(lidx), b->end_idx()) && !prompt_use(b,lidx) )

           UPblock[slidx] = false;

         // If we are not split up/down and all inputs are down, then we

         // are down

         if( !needs_split && !u3 )

           UPblock[slidx] = false;

       }  // end if phi is needed

       // Do not need a phi, so grab the reaching DEF

       else {

         // Grab predecessor block header

         n1 = b->pred(1);

         // Grab the appropriate reaching def info for k

         pred = _cfg._bbs[n1->_idx];

         pidx = pred->_pre_order;

         Node **Ltmp = Reaches[pidx];

         bool  *Utmp = UP[pidx];

         // reset the Reaches & UP entries

         Reachblock[slidx] = Ltmp[slidx];

         UPblock[slidx] = Utmp[slidx];

       }  // end else no Phi is needed

     }  // end for all spilling live ranges

     // DEBUG

 #ifndef PRODUCT

     if(trace_spilling()) {

       tty->print("/`\nBlock %d: ", b->_pre_order);

       tty->print("Reaching Definitions after Phi handling\n");

       for( uint x = 0; x < spill_cnt; x++ ) {

         tty->print("Spill Idx %d: UP %d: Node\n",x,UPblock[x]);

         if( Reachblock[x] )

           Reachblock[x]->dump();

         else

           tty->print("Undefined\n");

       }

     }

 #endif

     //----------Non-Phi Node Splitting----------

     // Since phi-nodes have now been handled, the Reachblock array for this

     // block is initialized with the correct starting value for the defs which

     // reach non-phi instructions in this block.  Thus, process non-phi

     // instructions normally, inserting SpillCopy nodes for all spill

     // locations.

     // Memoize any DOWN reaching definitions for use as DEBUG info

     for( insidx = 0; insidx < spill_cnt; insidx++ ) {

       debug_defs[insidx] = (UPblock[insidx]) ? NULL : Reachblock[insidx];

       if( UPblock[insidx] )     // Memoize UP decision at block start

         UP_entry[insidx]->set( b->_pre_order );

     }

     //----------Walk Instructions in the Block and Split----------

     // For all non-phi instructions in the block

     for( insidx = 1; insidx <= b->end_idx(); insidx++ ) {

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

       // Find the defining Node's live range index

       uint defidx = Find_id(n);

       uint cnt = n->req();

       if( n->is_Phi() ) {

         // Skip phi nodes after removing dead copies.

         if( defidx < _maxlrg ) {

           // Check for useless Phis.  These appear if we spill, then

           // coalesce away copies.  Dont touch Phis in spilling live

           // ranges; they are busy getting modifed in this pass.

           if( lrgs(defidx).reg() < LRG::SPILL_REG ) {

             uint i;

             Node *u = NULL;

             // Look for the Phi merging 2 unique inputs

             for( i = 1; i < cnt; i++ ) {

               // Ignore repeats and self

               if( n->in(i) != u && n->in(i) != n ) {

                 // Found a unique input

                 if( u != NULL ) // If it's the 2nd, bail out

                   break;

                 u = n->in(i);   // Else record it

               }

             }

             assert( u, "at least 1 valid input expected" );

             if( i >= cnt ) {    // Found one unique input

               assert(Find_id(n) == Find_id(u), "should be the same lrg");

               n->replace_by(u); // Then replace with unique input

               n->disconnect_inputs(NULL);

               b->_nodes.remove(insidx);

               insidx--;

               b->_ihrp_index--;

               b->_fhrp_index--;

             }

           }

         }

         continue;

       }

       assert( insidx > b->_ihrp_index ||

               (b->_reg_pressure < (uint)INTPRESSURE) ||

               b->_ihrp_index > 4000000 ||

               b->_ihrp_index >= b->end_idx() ||

               !b->_nodes[b->_ihrp_index]->is_Proj(), "" );

       assert( insidx > b->_fhrp_index ||

               (b->_freg_pressure < (uint)FLOATPRESSURE) ||

               b->_fhrp_index > 4000000 ||

               b->_fhrp_index >= b->end_idx() ||

               !b->_nodes[b->_fhrp_index]->is_Proj(), "" );

       // ********** Handle Crossing HRP Boundry **********

       if( (insidx == b->_ihrp_index) || (insidx == b->_fhrp_index) ) {

         for( slidx = 0; slidx < spill_cnt; slidx++ ) {

           // Check for need to split at HRP boundry - split if UP

           n1 = Reachblock[slidx];

           // bail out if no reaching DEF

           if( n1 == NULL ) continue;

           // bail out if live range is 'isolated' around inner loop

           uint lidx = lidxs.at(slidx);

           // If live range is currently UP

           if( UPblock[slidx] ) {

             // set location to insert spills at

             // SPLIT DOWN HERE - NO CISC SPILL

             if( is_high_pressure( b, &lrgs(lidx), insidx ) &&

                 !n1->rematerialize() ) {

               // If there is already a valid stack definition available, use it

               if( debug_defs[slidx] != NULL ) {

                 Reachblock[slidx] = debug_defs[slidx];

               }

               else {

                 // Insert point is just past last use or def in the block

                 int insert_point = insidx-1;

                 while( insert_point > 0 ) {

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

                   // Hit top of block?  Quit going backwards

                   if( n->is_Phi() ) break;

                   // Found a def?  Better split after it.

                   if( n2lidx(n) == lidx ) break;

                   // Look for a use

                   uint i;

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

                     if( n2lidx(n->in(i)) == lidx )

                       break;

                   // Found a use?  Better split after it.

                   if( i < n->req() ) break;

                   insert_point--;

                 }

                 maxlrg = split_DEF( n1, b, insert_point, maxlrg, Reachblock, debug_defs, splits, slidx);

                 // If it wasn't split bail

                 if (!maxlrg) {

                   return 0;

                 }

                 insidx++;

               }

               // This is a new DEF, so update UP

               UPblock[slidx] = false;

 #ifndef PRODUCT

               // DEBUG

               if( trace_spilling() ) {

                 tty->print("\nNew Split DOWN DEF of Spill Idx ");

                 tty->print("%d, UP %d:\n",slidx,false);

                 n1->dump();

               }

 #endif

             }

           }  // end if LRG is UP

         }  // end for all spilling live ranges

         assert( b->_nodes[insidx] == n, "got insidx set incorrectly" );

       }  // end if crossing HRP Boundry

       // If the LRG index is oob, then this is a new spillcopy, skip it.

       if( defidx >= _maxlrg ) {

         continue;

       }

       LRG &deflrg = lrgs(defidx);

       uint copyidx = n->is_Copy();

       // Remove coalesced copy from CFG

       if( copyidx && defidx == n2lidx(n->in(copyidx)) ) {

         n->replace_by( n->in(copyidx) );

         n->set_req( copyidx, NULL );

         b->_nodes.remove(insidx--);

         b->_ihrp_index--; // Adjust the point where we go hi-pressure

         b->_fhrp_index--;

         continue;

       }

 #define DERIVED 0

       // ********** Handle USES **********

       bool nullcheck = false;

       // Implicit null checks never use the spilled value

       if( n->is_MachNullCheck() )

         nullcheck = true;

       if( !nullcheck ) {

         // Search all inputs for a Spill-USE

         JVMState* jvms = n->jvms();

         uint oopoff = jvms ? jvms->oopoff() : cnt;

         uint old_last = cnt - 1;

         for( inpidx = 1; inpidx < cnt; inpidx++ ) {

           // Derived/base pairs may be added to our inputs during this loop.

           // If inpidx > old_last, then one of these new inputs is being

           // handled. Skip the derived part of the pair, but process

           // the base like any other input.

           if( inpidx > old_last && ((inpidx - oopoff) & 1) == DERIVED ) {

             continue;  // skip derived_debug added below

           }

           // Get lidx of input

           uint useidx = Find_id(n->in(inpidx));

           // Not a brand-new split, and it is a spill use

           if( useidx < _maxlrg && lrgs(useidx).reg() >= LRG::SPILL_REG ) {

             // Check for valid reaching DEF

             slidx = lrg2reach[useidx];

             Node *def = Reachblock[slidx];

             assert( def != NULL, "Using Undefined Value in Split()\n");

             // (+++) %%%% remove this in favor of pre-pass in matcher.cpp

             // monitor references do not care where they live, so just hook

             if ( jvms && jvms->is_monitor_use(inpidx) ) {

               // The effect of this clone is to drop the node out of the block,

               // so that the allocator does not see it anymore, and therefore

               // does not attempt to assign it a register.

               def = def->clone();

               _names.extend(def->_idx,0);

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

               n->set_req(inpidx, def);

               if (C->check_node_count(NodeLimitFudgeFactor, out_of_nodes)) {

                 return 0;

               }

               continue;

             }

             // Rematerializable?  Then clone def at use site instead

             // of store/load

             if( def->rematerialize() ) {

               int old_size = b->_nodes.size();

               def = split_Rematerialize( def, b, insidx, maxlrg, splits, slidx, lrg2reach, Reachblock, true );

               if( !def ) return 0; // Bail out

               insidx += b->_nodes.size()-old_size;

             }

             MachNode *mach = n->is_Mach() ? n->as_Mach() : NULL;

             // Base pointers and oopmap references do not care where they live.

             if ((inpidx >= oopoff) ||

                 (mach && mach->ideal_Opcode() == Op_AddP && inpidx == AddPNode::Base)) {

               if (def->rematerialize() && lrgs(useidx)._was_spilled2) {

                 // This def has been rematerialized a couple of times without

                 // progress. It doesn't care if it lives UP or DOWN, so

                 // spill it down now.

                 maxlrg = split_USE(def,b,n,inpidx,maxlrg,false,false,splits,slidx);

                 // If it wasn't split bail

                 if (!maxlrg) {

                   return 0;

                 }

                 insidx++;  // Reset iterator to skip USE side split

               } else {

                 // Just hook the def edge

                 n->set_req(inpidx, def);

               }

               if (inpidx >= oopoff) {

                 // After oopoff, we have derived/base pairs.  We must mention all

                 // derived pointers here as derived/base pairs for GC.  If the

                 // derived value is spilling and we have a copy both in Reachblock

                 // (called here 'def') and debug_defs[slidx] we need to mention

                 // both in derived/base pairs or kill one.

                 Node *derived_debug = debug_defs[slidx];

                 if( ((inpidx - oopoff) & 1) == DERIVED && // derived vs base?

                     mach && mach->ideal_Opcode() != Op_Halt &&

                     derived_debug != NULL &&

                     derived_debug != def ) { // Actual 2nd value appears

                   // We have already set 'def' as a derived value.

                   // Also set debug_defs[slidx] as a derived value.

                   uint k;

                   for( k = oopoff; k < cnt; k += 2 )

                     if( n->in(k) == derived_debug )

                       break;      // Found an instance of debug derived

                   if( k == cnt ) {// No instance of debug_defs[slidx]

                     // Add a derived/base pair to cover the debug info.

                     // We have to process the added base later since it is not

                     // handled yet at this point but skip derived part.

                     assert(((n->req() - oopoff) & 1) == DERIVED,

                            "must match skip condition above");

                     n->add_req( derived_debug );   // this will be skipped above

                     n->add_req( n->in(inpidx+1) ); // this will be processed

                     // Increment cnt to handle added input edges on

                     // subsequent iterations.

                     cnt += 2;

                   }

                 }

               }

               continue;

             }

             // Special logic for DEBUG info

             if( jvms && b->_freq > BLOCK_FREQUENCY(0.5) ) {

               uint debug_start = jvms->debug_start();

               // If this is debug info use & there is a reaching DOWN def

               if ((debug_start <= inpidx) && (debug_defs[slidx] != NULL)) {

                 assert(inpidx < oopoff, "handle only debug info here");

                 // Just hook it in & move on

                 n->set_req(inpidx, debug_defs[slidx]);

                 // (Note that this can make two sides of a split live at the

                 // same time: The debug def on stack, and another def in a

                 // register.  The GC needs to know about both of them, but any

                 // derived pointers after oopoff will refer to only one of the

                 // two defs and the GC would therefore miss the other.  Thus

                 // this hack is only allowed for debug info which is Java state

                 // and therefore never a derived pointer.)

                 continue;

               }

             }

             // Grab register mask info

             const RegMask &dmask = def->out_RegMask();

             const RegMask &umask = n->in_RegMask(inpidx);

             assert(inpidx < oopoff, "cannot use-split oop map info");

             bool dup = UPblock[slidx];

             bool uup = umask.is_UP();

             // Need special logic to handle bound USES. Insert a split at this

             // bound use if we can't rematerialize the def, or if we need the

             // split to form a misaligned pair.

             if( !umask.is_AllStack() &&

                 (int)umask.Size() <= lrgs(useidx).num_regs() &&

                 (!def->rematerialize() ||

                  umask.is_misaligned_Pair())) {

               // These need a Split regardless of overlap or pressure

               // SPLIT - NO DEF - NO CISC SPILL

               maxlrg = split_USE(def,b,n,inpidx,maxlrg,dup,false, splits,slidx);

               // If it wasn't split bail

               if (!maxlrg) {

                 return 0;

               }

               insidx++;  // Reset iterator to skip USE side split

               continue;

             }

             // Here is the logic chart which describes USE Splitting:

             // 0 = false or DOWN, 1 = true or UP

             //

             // Overlap | DEF | USE | Action

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

             //    0    |  0  |  0  | Copy - mem -> mem

             //    0    |  0  |  1  | Split-UP - Check HRP

             //    0    |  1  |  0  | Split-DOWN - Debug Info?

             //    0    |  1  |  1  | Copy - reg -> reg

             //    1    |  0  |  0  | Reset Input Edge (no Split)

             //    1    |  0  |  1  | Split-UP - Check HRP

             //    1    |  1  |  0  | Split-DOWN - Debug Info?

             //    1    |  1  |  1  | Reset Input Edge (no Split)

             //

             // So, if (dup == uup), then overlap test determines action,

             // with true being no split, and false being copy. Else,

             // if DEF is DOWN, Split-UP, and check HRP to decide on

             // resetting DEF. Finally if DEF is UP, Split-DOWN, with

             // special handling for Debug Info.

             if( dup == uup ) {

               if( dmask.overlap(umask) ) {

                 // Both are either up or down, and there is overlap, No Split

                 n->set_req(inpidx, def);

               }

               else {  // Both are either up or down, and there is no overlap

                 if( dup ) {  // If UP, reg->reg copy

                   // COPY ACROSS HERE - NO DEF - NO CISC SPILL

                   maxlrg = split_USE(def,b,n,inpidx,maxlrg,false,false, splits,slidx);

                   // If it wasn't split bail

                   if (!maxlrg) {

                     return 0;

                   }

                   insidx++;  // Reset iterator to skip USE side split

                 }

                 else {       // DOWN, mem->mem copy

                   // COPY UP & DOWN HERE - NO DEF - NO CISC SPILL

                   // First Split-UP to move value into Register

                   uint def_ideal = def->ideal_reg();

                   const RegMask* tmp_rm = Matcher::idealreg2regmask[def_ideal];

                   Node *spill = new (C) MachSpillCopyNode(def, dmask, *tmp_rm);

                   insert_proj( b, insidx, spill, maxlrg );

                   // Then Split-DOWN as if previous Split was DEF

                   maxlrg = split_USE(spill,b,n,inpidx,maxlrg,false,false, splits,slidx);

                   // If it wasn't split bail

                   if (!maxlrg) {

                     return 0;

                   }

                   insidx += 2;  // Reset iterator to skip USE side splits

                 }

               }  // End else no overlap

             }  // End if dup == uup

             // dup != uup, so check dup for direction of Split

             else {

               if( dup ) {  // If UP, Split-DOWN and check Debug Info

                 // If this node is already a SpillCopy, just patch the edge

                 // except the case of spilling to stack.

                 if( n->is_SpillCopy() ) {

                   RegMask tmp_rm(umask);

                   tmp_rm.SUBTRACT(Matcher::STACK_ONLY_mask);

                   if( dmask.overlap(tmp_rm) ) {

                     if( def != n->in(inpidx) ) {

                       n->set_req(inpidx, def);

                     }

                     continue;

                   }

                 }

                 // COPY DOWN HERE - NO DEF - NO CISC SPILL

                 maxlrg = split_USE(def,b,n,inpidx,maxlrg,false,false, splits,slidx);

                 // If it wasn't split bail

                 if (!maxlrg) {

                   return 0;

                 }

                 insidx++;  // Reset iterator to skip USE side split

                 // Check for debug-info split.  Capture it for later

                 // debug splits of the same value

                 if (jvms && jvms->debug_start() <= inpidx && inpidx < oopoff)

                   debug_defs[slidx] = n->in(inpidx);

               }

               else {       // DOWN, Split-UP and check register pressure

                 if( is_high_pressure( b, &lrgs(useidx), insidx ) ) {

                   // COPY UP HERE - NO DEF - CISC SPILL

                   maxlrg = split_USE(def,b,n,inpidx,maxlrg,true,true, splits,slidx);

                   // If it wasn't split bail

                   if (!maxlrg) {

                     return 0;

                   }

                   insidx++;  // Reset iterator to skip USE side split

                 } else {                          // LRP

                   // COPY UP HERE - WITH DEF - NO CISC SPILL

                   maxlrg = split_USE(def,b,n,inpidx,maxlrg,true,false, splits,slidx);

                   // If it wasn't split bail

                   if (!maxlrg) {

                     return 0;

                   }

                   // Flag this lift-up in a low-pressure block as

                   // already-spilled, so if it spills again it will

                   // spill hard (instead of not spilling hard and

                   // coalescing away).

                   set_was_spilled(n->in(inpidx));

                   // Since this is a new DEF, update Reachblock & UP

                   Reachblock[slidx] = n->in(inpidx);

                   UPblock[slidx] = true;

                   insidx++;  // Reset iterator to skip USE side split

                 }

               }  // End else DOWN

             }  // End dup != uup

           }  // End if Spill USE

         }  // End For All Inputs

       }  // End If not nullcheck

       // ********** Handle DEFS **********

       // DEFS either Split DOWN in HRP regions or when the LRG is bound, or

       // just reset the Reaches info in LRP regions.  DEFS must always update

       // UP info.

       if( deflrg.reg() >= LRG::SPILL_REG ) {    // Spilled?

         uint slidx = lrg2reach[defidx];

         // Add to defs list for later assignment of new live range number

         defs->push(n);

         // Set a flag on the Node indicating it has already spilled.

         // Only do it for capacity spills not conflict spills.

         if( !deflrg._direct_conflict )

           set_was_spilled(n);

         assert(!n->is_Phi(),"Cannot insert Phi into DEFS list");

         // Grab UP info for DEF

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

         bool defup = dmask.is_UP();

         // Only split at Def if this is a HRP block or bound (and spilled once)

         if( !n->rematerialize() &&

             (((dmask.is_bound1() || dmask.is_bound2() || dmask.is_misaligned_Pair()) &&

              (deflrg._direct_conflict || deflrg._must_spill)) ||

              // Check for LRG being up in a register and we are inside a high

              // pressure area.  Spill it down immediately.

              (defup && is_high_pressure(b,&deflrg,insidx))) ) {

           assert( !n->rematerialize(), "" );

           assert( !n->is_SpillCopy(), "" );

           // Do a split at the def site.

           maxlrg = split_DEF( n, b, insidx, maxlrg, Reachblock, debug_defs, splits, slidx );

           // If it wasn't split bail

           if (!maxlrg) {

             return 0;

           }

           // Split DEF's Down

           UPblock[slidx] = 0;

 #ifndef PRODUCT

           // DEBUG

           if( trace_spilling() ) {

             tty->print("\nNew Split DOWN DEF of Spill Idx ");

             tty->print("%d, UP %d:\n",slidx,false);

             n->dump();

           }

 #endif

         }

         else {                  // Neither bound nor HRP, must be LRP

           // otherwise, just record the def

           Reachblock[slidx] = n;

           // UP should come from the outRegmask() of the DEF

           UPblock[slidx] = defup;

           // Update debug list of reaching down definitions, kill if DEF is UP

           debug_defs[slidx] = defup ? NULL : n;

 #ifndef PRODUCT

           // DEBUG

           if( trace_spilling() ) {

             tty->print("\nNew DEF of Spill Idx ");

             tty->print("%d, UP %d:\n",slidx,defup);

             n->dump();

           }

 #endif

         }  // End else LRP

       }  // End if spill def

       // ********** Split Left Over Mem-Mem Moves **********

       // Check for mem-mem copies and split them now.  Do not do this

       // to copies about to be spilled; they will be Split shortly.

       if( copyidx ) {

         Node *use = n->in(copyidx);

         uint useidx = Find_id(use);

         if( useidx < _maxlrg &&       // This is not a new split

             OptoReg::is_stack(deflrg.reg()) &&

             deflrg.reg() < LRG::SPILL_REG ) { // And DEF is from stack

           LRG &uselrg = lrgs(useidx);

           if( OptoReg::is_stack(uselrg.reg()) &&

               uselrg.reg() < LRG::SPILL_REG && // USE is from stack

               deflrg.reg() != uselrg.reg() ) { // Not trivially removed

             uint def_ideal_reg = Matcher::base2reg[n->bottom_type()->base()];

             const RegMask &def_rm = *Matcher::idealreg2regmask[def_ideal_reg];

             const RegMask &use_rm = n->in_RegMask(copyidx);

             if( def_rm.overlap(use_rm) && n->is_SpillCopy() ) {  // Bug 4707800, 'n' may be a storeSSL

               if (C->check_node_count(NodeLimitFudgeFactor, out_of_nodes)) {  // Check when generating nodes

                 return 0;

               }

               Node *spill = new (C) MachSpillCopyNode(use,use_rm,def_rm);

               n->set_req(copyidx,spill);

               n->as_MachSpillCopy()->set_in_RegMask(def_rm);

               // Put the spill just before the copy

               insert_proj( b, insidx++, spill, maxlrg++ );

             }

           }

         }

       }

     }  // End For All Instructions in Block - Non-PHI Pass

     // Check if each LRG is live out of this block so as not to propagate

     // beyond the last use of a LRG.

     for( slidx = 0; slidx < spill_cnt; slidx++ ) {

       uint defidx = lidxs.at(slidx);

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

       if( !liveout->member(defidx) ) {

 #ifdef ASSERT

         // The index defidx is not live.  Check the liveout array to ensure that

         // it contains no members which compress to defidx.  Finding such an

         // instance may be a case to add liveout adjustment in compress_uf_map().

         // See 5063219.

         uint member;

         IndexSetIterator isi(liveout);

         while ((member = isi.next()) != 0) {

           assert(defidx != Find_const(member), "Live out member has not been compressed");

         }

 #endif

         Reachblock[slidx] = NULL;

       } else {

         assert(Reachblock[slidx] != NULL,"No reaching definition for liveout value");

       }

     }

 #ifndef PRODUCT

     if( trace_spilling() )

       b->dump();

 #endif

   }  // End For All Blocks

   //----------PASS 2----------

   // Reset all DEF live range numbers here

   for( insidx = 0; insidx < defs->size(); insidx++ ) {

     // Grab the def

     n1 = defs->at(insidx);

     // Set new lidx for DEF

     new_lrg(n1, maxlrg++);

   }

   //----------Phi Node Splitting----------

   // Clean up a phi here, and assign a new live range number

   // Cycle through this block's predecessors, collecting Reaches

   // info for each spilled LRG and update edges.

   // Walk the phis list to patch inputs, split phis, and name phis

   for( insidx = 0; insidx < phis->size(); insidx++ ) {

     Node *phi = phis->at(insidx);

     assert(phi->is_Phi(),"This list must only contain Phi Nodes");

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

     // Grab the live range number

     uint lidx = Find_id(phi);

     uint slidx = lrg2reach[lidx];

     // Update node to lidx map

     new_lrg(phi, maxlrg++);

     // Get PASS1's up/down decision for the block.

     int phi_up = !!UP_entry[slidx]->test(b->_pre_order);

     // Force down if double-spilling live range

     if( lrgs(lidx)._was_spilled1 )

       phi_up = false;

     // When splitting a Phi we an split it normal or "inverted".

     // An inverted split makes the splits target the Phi's UP/DOWN

     // sense inverted; then the Phi is followed by a final def-side

     // split to invert back.  It changes which blocks the spill code

     // goes in.

     // Walk the predecessor blocks and assign the reaching def to the Phi.

     // Split Phi nodes by placing USE side splits wherever the reaching

     // DEF has the wrong UP/DOWN value.

     for( uint i = 1; i < b->num_preds(); i++ ) {

       // Get predecessor block pre-order number

       Block *pred = _cfg._bbs[b->pred(i)->_idx];

       pidx = pred->_pre_order;

       // Grab reaching def

       Node *def = Reaches[pidx][slidx];

       assert( def, "must have reaching def" );

       // If input up/down sense and reg-pressure DISagree

       if( def->rematerialize() ) {

         def = split_Rematerialize( def, pred, pred->end_idx(), maxlrg, splits, slidx, lrg2reach, Reachblock, false );

         if( !def ) return 0;    // Bail out

       }

       // Update the Phi's input edge array

       phi->set_req(i,def);

       // Grab the UP/DOWN sense for the input

       u1 = UP[pidx][slidx];

       if( u1 != (phi_up != 0)) {

         maxlrg = split_USE(def, b, phi, i, maxlrg, !u1, false, splits,slidx);

         // If it wasn't split bail

         if (!maxlrg) {

           return 0;

         }

       }

     }  // End for all inputs to the Phi

   }  // End for all Phi Nodes

   // Update _maxlrg to save Union asserts

   _maxlrg = maxlrg;

   //----------PASS 3----------

   // Pass over all Phi's to union the live ranges

   for( insidx = 0; insidx < phis->size(); insidx++ ) {

     Node *phi = phis->at(insidx);

     assert(phi->is_Phi(),"This list must only contain Phi Nodes");

     // Walk all inputs to Phi and Union input live range with Phi live range

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

       // Grab the input node

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

       assert( n, "" );

       uint lidx = Find(n);

       uint pidx = Find(phi);

       if( lidx < pidx )

         Union(n, phi);

       else if( lidx > pidx )

         Union(phi, n);

     }  // End for all inputs to the Phi Node

   }  // End for all Phi Nodes

   // Now union all two address instructions

   for( insidx = 0; insidx < defs->size(); insidx++ ) {

     // Grab the def

     n1 = defs->at(insidx);

     // Set new lidx for DEF & handle 2-addr instructions

     if( n1->is_Mach() && ((twoidx = n1->as_Mach()->two_adr()) != 0) ) {

       assert( Find(n1->in(twoidx)) < maxlrg,"Assigning bad live range index");

       // Union the input and output live ranges

       uint lr1 = Find(n1);

       uint lr2 = Find(n1->in(twoidx));

       if( lr1 < lr2 )

         Union(n1, n1->in(twoidx));

       else if( lr1 > lr2 )

         Union(n1->in(twoidx), n1);

     }  // End if two address

   }  // End for all defs

   // DEBUG

 #ifdef ASSERT

   // Validate all live range index assignments

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

     b  = _cfg._blocks[bidx];

     for( insidx = 0; insidx <= b->end_idx(); insidx++ ) {

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

       uint defidx = Find(n);

       assert(defidx < _maxlrg,"Bad live range index in Split");

       assert(defidx < maxlrg,"Bad live range index in Split");

     }

   }

   // Issue a warning if splitting made no progress

   int noprogress = 0;

   for( slidx = 0; slidx < spill_cnt; slidx++ ) {

     if( PrintOpto && WizardMode && splits.at(slidx) == 0 ) {

       tty->print_cr("Failed to split live range %d", lidxs.at(slidx));

       //BREAKPOINT;

     }

     else {

       noprogress++;

     }

   }

   if(!noprogress) {

     tty->print_cr("Failed to make progress in Split");

     //BREAKPOINT;

   }

 #endif

   // Return updated count of live ranges

   return maxlrg;

 }