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

 /*

  * Copyright (c) 1997, 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.

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  */

 #include "precompiled.hpp"

 #include "memory/allocation.inline.hpp"

 #include "opto/addnode.hpp"

 #include "opto/callnode.hpp"

 #include "opto/connode.hpp"

 #include "opto/idealGraphPrinter.hpp"

 #include "opto/matcher.hpp"

 #include "opto/memnode.hpp"

 #include "opto/opcodes.hpp"

 #include "opto/regmask.hpp"

 #include "opto/rootnode.hpp"

 #include "opto/runtime.hpp"

 #include "opto/type.hpp"

 #include "opto/vectornode.hpp"

 #include "runtime/atomic.hpp"

 #include "runtime/os.hpp"

 #ifdef TARGET_ARCH_MODEL_x86_32

 # include "adfiles/ad_x86_32.hpp"

 #endif

 #ifdef TARGET_ARCH_MODEL_x86_64

 # include "adfiles/ad_x86_64.hpp"

 #endif

 #ifdef TARGET_ARCH_MODEL_sparc

 # include "adfiles/ad_sparc.hpp"

 #endif

 #ifdef TARGET_ARCH_MODEL_zero

 # include "adfiles/ad_zero.hpp"

 #endif

 #ifdef TARGET_ARCH_MODEL_arm

 # include "adfiles/ad_arm.hpp"

 #endif

 #ifdef TARGET_ARCH_MODEL_ppc

 # include "adfiles/ad_ppc.hpp"

 #endif

 OptoReg::Name OptoReg::c_frame_pointer;

 const RegMask *Matcher::idealreg2regmask[_last_machine_leaf];

 RegMask Matcher::mreg2regmask[_last_Mach_Reg];

 RegMask Matcher::STACK_ONLY_mask;

 RegMask Matcher::c_frame_ptr_mask;

 const uint Matcher::_begin_rematerialize = _BEGIN_REMATERIALIZE;

 const uint Matcher::_end_rematerialize   = _END_REMATERIALIZE;

 //---------------------------Matcher-------------------------------------------

 Matcher::Matcher( Node_List &proj_list ) :

   PhaseTransform( Phase::Ins_Select ),

 #ifdef ASSERT

   _old2new_map(C->comp_arena()),

   _new2old_map(C->comp_arena()),

 #endif

   _shared_nodes(C->comp_arena()),

   _reduceOp(reduceOp), _leftOp(leftOp), _rightOp(rightOp),

   _swallowed(swallowed),

   _begin_inst_chain_rule(_BEGIN_INST_CHAIN_RULE),

   _end_inst_chain_rule(_END_INST_CHAIN_RULE),

   _must_clone(must_clone), _proj_list(proj_list),

   _register_save_policy(register_save_policy),

   _c_reg_save_policy(c_reg_save_policy),

   _register_save_type(register_save_type),

   _ruleName(ruleName),

   _allocation_started(false),

   _states_arena(Chunk::medium_size),

   _visited(&_states_arena),

   _shared(&_states_arena),

   _dontcare(&_states_arena) {

   C->set_matcher(this);

   idealreg2spillmask  [Op_RegI] = NULL;

   idealreg2spillmask  [Op_RegN] = NULL;

   idealreg2spillmask  [Op_RegL] = NULL;

   idealreg2spillmask  [Op_RegF] = NULL;

   idealreg2spillmask  [Op_RegD] = NULL;

   idealreg2spillmask  [Op_RegP] = NULL;

   idealreg2spillmask  [Op_VecS] = NULL;

   idealreg2spillmask  [Op_VecD] = NULL;

   idealreg2spillmask  [Op_VecX] = NULL;

   idealreg2spillmask  [Op_VecY] = NULL;

   idealreg2debugmask  [Op_RegI] = NULL;

   idealreg2debugmask  [Op_RegN] = NULL;

   idealreg2debugmask  [Op_RegL] = NULL;

   idealreg2debugmask  [Op_RegF] = NULL;

   idealreg2debugmask  [Op_RegD] = NULL;

   idealreg2debugmask  [Op_RegP] = NULL;

   idealreg2debugmask  [Op_VecS] = NULL;

   idealreg2debugmask  [Op_VecD] = NULL;

   idealreg2debugmask  [Op_VecX] = NULL;

   idealreg2debugmask  [Op_VecY] = NULL;

   idealreg2mhdebugmask[Op_RegI] = NULL;

   idealreg2mhdebugmask[Op_RegN] = NULL;

   idealreg2mhdebugmask[Op_RegL] = NULL;

   idealreg2mhdebugmask[Op_RegF] = NULL;

   idealreg2mhdebugmask[Op_RegD] = NULL;

   idealreg2mhdebugmask[Op_RegP] = NULL;

   idealreg2mhdebugmask[Op_VecS] = NULL;

   idealreg2mhdebugmask[Op_VecD] = NULL;

   idealreg2mhdebugmask[Op_VecX] = NULL;

   idealreg2mhdebugmask[Op_VecY] = NULL;

   debug_only(_mem_node = NULL;)   // Ideal memory node consumed by mach node

 }

 //------------------------------warp_incoming_stk_arg------------------------

 // This warps a VMReg into an OptoReg::Name

 OptoReg::Name Matcher::warp_incoming_stk_arg( VMReg reg ) {

   OptoReg::Name warped;

   if( reg->is_stack() ) {  // Stack slot argument?

     warped = OptoReg::add(_old_SP, reg->reg2stack() );

     warped = OptoReg::add(warped, C->out_preserve_stack_slots());

     if( warped >= _in_arg_limit )

       _in_arg_limit = OptoReg::add(warped, 1); // Bump max stack slot seen

     if (!RegMask::can_represent_arg(warped)) {

       // the compiler cannot represent this method's calling sequence

       C->record_method_not_compilable_all_tiers("unsupported incoming calling sequence");

       return OptoReg::Bad;

     }

     return warped;

   }

   return OptoReg::as_OptoReg(reg);

 }

 //---------------------------compute_old_SP------------------------------------

 OptoReg::Name Compile::compute_old_SP() {

   int fixed    = fixed_slots();

   int preserve = in_preserve_stack_slots();

   return OptoReg::stack2reg(round_to(fixed + preserve, Matcher::stack_alignment_in_slots()));

 }

 #ifdef ASSERT

 void Matcher::verify_new_nodes_only(Node* xroot) {

   // Make sure that the new graph only references new nodes

   ResourceMark rm;

   Unique_Node_List worklist;

   VectorSet visited(Thread::current()->resource_area());

   worklist.push(xroot);

   while (worklist.size() > 0) {

     Node* n = worklist.pop();

     visited <<= n->_idx;

     assert(C->node_arena()->contains(n), "dead node");

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

       Node* in = n->in(j);

       if (in != NULL) {

         assert(C->node_arena()->contains(in), "dead node");

         if (!visited.test(in->_idx)) {

           worklist.push(in);

         }

       }

     }

   }

 }

 #endif

 //---------------------------match---------------------------------------------

 void Matcher::match( ) {

   if( MaxLabelRootDepth < 100 ) { // Too small?

     assert(false, "invalid MaxLabelRootDepth, increase it to 100 minimum");

     MaxLabelRootDepth = 100;

   }

   // One-time initialization of some register masks.

   init_spill_mask( C->root()->in(1) );

   _return_addr_mask = return_addr();

 #ifdef _LP64

   // Pointers take 2 slots in 64-bit land

   _return_addr_mask.Insert(OptoReg::add(return_addr(),1));

 #endif

   // Map a Java-signature return type into return register-value

   // machine registers for 0, 1 and 2 returned values.

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

   if( range->cnt() > TypeFunc::Parms ) { // If not a void function

     // Get ideal-register return type

     int ireg = range->field_at(TypeFunc::Parms)->ideal_reg();

     // Get machine return register

     uint sop = C->start()->Opcode();

     OptoRegPair regs = return_value(ireg, false);

     // And mask for same

     _return_value_mask = RegMask(regs.first());

     if( OptoReg::is_valid(regs.second()) )

       _return_value_mask.Insert(regs.second());

   }

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

   // Frame Layout

   // Need the method signature to determine the incoming argument types,

   // because the types determine which registers the incoming arguments are

   // in, and this affects the matched code.

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

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

   BasicType *sig_bt        = NEW_RESOURCE_ARRAY( BasicType, argcnt );

   VMRegPair *vm_parm_regs  = NEW_RESOURCE_ARRAY( VMRegPair, argcnt );

   _parm_regs               = NEW_RESOURCE_ARRAY( OptoRegPair, argcnt );

   _calling_convention_mask = NEW_RESOURCE_ARRAY( RegMask, argcnt );

   uint i;

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

     sig_bt[i] = domain->field_at(i+TypeFunc::Parms)->basic_type();

   }

   // Pass array of ideal registers and length to USER code (from the AD file)

   // that will convert this to an array of register numbers.

   const StartNode *start = C->start();

   start->calling_convention( sig_bt, vm_parm_regs, argcnt );

 #ifdef ASSERT

   // Sanity check users' calling convention.  Real handy while trying to

   // get the initial port correct.

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

       if( !vm_parm_regs[i].first()->is_valid() && !vm_parm_regs[i].second()->is_valid() ) {

         assert(domain->field_at(i+TypeFunc::Parms)==Type::HALF, "only allowed on halve" );

         _parm_regs[i].set_bad();

         continue;

       }

       VMReg parm_reg = vm_parm_regs[i].first();

       assert(parm_reg->is_valid(), "invalid arg?");

       if (parm_reg->is_reg()) {

         OptoReg::Name opto_parm_reg = OptoReg::as_OptoReg(parm_reg);

         assert(can_be_java_arg(opto_parm_reg) ||

                C->stub_function() == CAST_FROM_FN_PTR(address, OptoRuntime::rethrow_C) ||

                opto_parm_reg == inline_cache_reg(),

                "parameters in register must be preserved by runtime stubs");

       }

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

         assert(parm_reg != vm_parm_regs[j].first(),

                "calling conv. must produce distinct regs");

       }

     }

   }

 #endif

   // Do some initial frame layout.

   // Compute the old incoming SP (may be called FP) as

   //   OptoReg::stack0() + locks + in_preserve_stack_slots + pad2.

   _old_SP = C->compute_old_SP();

   assert( is_even(_old_SP), "must be even" );

   // Compute highest incoming stack argument as

   //   _old_SP + out_preserve_stack_slots + incoming argument size.

   _in_arg_limit = OptoReg::add(_old_SP, C->out_preserve_stack_slots());

   assert( is_even(_in_arg_limit), "out_preserve must be even" );

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

     // Permit args to have no register

     _calling_convention_mask[i].Clear();

     if( !vm_parm_regs[i].first()->is_valid() && !vm_parm_regs[i].second()->is_valid() ) {

       continue;

     }

     // calling_convention returns stack arguments as a count of

     // slots beyond OptoReg::stack0()/VMRegImpl::stack0.  We need to convert this to

     // the allocators point of view, taking into account all the

     // preserve area, locks & pad2.

     OptoReg::Name reg1 = warp_incoming_stk_arg(vm_parm_regs[i].first());

     if( OptoReg::is_valid(reg1))

       _calling_convention_mask[i].Insert(reg1);

     OptoReg::Name reg2 = warp_incoming_stk_arg(vm_parm_regs[i].second());

     if( OptoReg::is_valid(reg2))

       _calling_convention_mask[i].Insert(reg2);

     // Saved biased stack-slot register number

     _parm_regs[i].set_pair(reg2, reg1);

   }

   // Finally, make sure the incoming arguments take up an even number of

   // words, in case the arguments or locals need to contain doubleword stack

   // slots.  The rest of the system assumes that stack slot pairs (in

   // particular, in the spill area) which look aligned will in fact be

   // aligned relative to the stack pointer in the target machine.  Double

   // stack slots will always be allocated aligned.

   _new_SP = OptoReg::Name(round_to(_in_arg_limit, RegMask::SlotsPerLong));

   // Compute highest outgoing stack argument as

   //   _new_SP + out_preserve_stack_slots + max(outgoing argument size).

   _out_arg_limit = OptoReg::add(_new_SP, C->out_preserve_stack_slots());

   assert( is_even(_out_arg_limit), "out_preserve must be even" );

   if (!RegMask::can_represent_arg(OptoReg::add(_out_arg_limit,-1))) {

     // the compiler cannot represent this method's calling sequence

     C->record_method_not_compilable("must be able to represent all call arguments in reg mask");

   }

   if (C->failing())  return;  // bailed out on incoming arg failure

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

   // Collect roots of matcher trees.  Every node for which

   // _shared[_idx] is cleared is guaranteed to not be shared, and thus

   // can be a valid interior of some tree.

   find_shared( C->root() );

   find_shared( C->top() );

   C->print_method("Before Matching");

   // Create new ideal node ConP #NULL even if it does exist in old space

   // to avoid false sharing if the corresponding mach node is not used.

   // The corresponding mach node is only used in rare cases for derived

   // pointers.

   Node* new_ideal_null = ConNode::make(C, TypePtr::NULL_PTR);

   // Swap out to old-space; emptying new-space

   Arena *old = C->node_arena()->move_contents(C->old_arena());

   // Save debug and profile information for nodes in old space:

   _old_node_note_array = C->node_note_array();

   if (_old_node_note_array != NULL) {

     C->set_node_note_array(new(C->comp_arena()) GrowableArray<Node_Notes*>

                            (C->comp_arena(), _old_node_note_array->length(),

                             0, NULL));

   }

   // Pre-size the new_node table to avoid the need for range checks.

   grow_new_node_array(C->unique());

   // Reset node counter so MachNodes start with _idx at 0

   int nodes = C->unique(); // save value

   C->set_unique(0);

   // Recursively match trees from old space into new space.

   // Correct leaves of new-space Nodes; they point to old-space.

   _visited.Clear();             // Clear visit bits for xform call

   C->set_cached_top_node(xform( C->top(), nodes ));

   if (!C->failing()) {

     Node* xroot =        xform( C->root(), 1 );

     if (xroot == NULL) {

       Matcher::soft_match_failure();  // recursive matching process failed

       C->record_method_not_compilable("instruction match failed");

     } else {

       // During matching shared constants were attached to C->root()

       // because xroot wasn't available yet, so transfer the uses to

       // the xroot.

       for( DUIterator_Fast jmax, j = C->root()->fast_outs(jmax); j < jmax; j++ ) {

         Node* n = C->root()->fast_out(j);

         if (C->node_arena()->contains(n)) {

           assert(n->in(0) == C->root(), "should be control user");

           n->set_req(0, xroot);

           --j;

           --jmax;

         }

       }

       // Generate new mach node for ConP #NULL

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

       _mach_null = match_tree(new_ideal_null);

       // Don't set control, it will confuse GCM since there are no uses.

       // The control will be set when this node is used first time

       // in find_base_for_derived().

       assert(_mach_null != NULL, "");

       C->set_root(xroot->is_Root() ? xroot->as_Root() : NULL);

 #ifdef ASSERT

       verify_new_nodes_only(xroot);

 #endif

     }

   }

   if (C->top() == NULL || C->root() == NULL) {

     C->record_method_not_compilable("graph lost"); // %%% cannot happen?

   }

   if (C->failing()) {

     // delete old;

     old->destruct_contents();

     return;

   }

   assert( C->top(), "" );

   assert( C->root(), "" );

   validate_null_checks();

   // Now smoke old-space

   NOT_DEBUG( old->destruct_contents() );

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

   // Set up save-on-entry registers

   Fixup_Save_On_Entry( );

 }

 //------------------------------Fixup_Save_On_Entry----------------------------

 // The stated purpose of this routine is to take care of save-on-entry

 // registers.  However, the overall goal of the Match phase is to convert into

 // machine-specific instructions which have RegMasks to guide allocation.

 // So what this procedure really does is put a valid RegMask on each input

 // to the machine-specific variations of all Return, TailCall and Halt

 // instructions.  It also adds edgs to define the save-on-entry values (and of

 // course gives them a mask).

 static RegMask *init_input_masks( uint size, RegMask &ret_adr, RegMask &fp ) {

   RegMask *rms = NEW_RESOURCE_ARRAY( RegMask, size );

   // Do all the pre-defined register masks

   rms[TypeFunc::Control  ] = RegMask::Empty;

   rms[TypeFunc::I_O      ] = RegMask::Empty;

   rms[TypeFunc::Memory   ] = RegMask::Empty;

   rms[TypeFunc::ReturnAdr] = ret_adr;

   rms[TypeFunc::FramePtr ] = fp;

   return rms;

 }

 //---------------------------init_first_stack_mask-----------------------------

 // Create the initial stack mask used by values spilling to the stack.

 // Disallow any debug info in outgoing argument areas by setting the

 // initial mask accordingly.

 void Matcher::init_first_stack_mask() {

   // Allocate storage for spill masks as masks for the appropriate load type.

   RegMask *rms = (RegMask*)C->comp_arena()->Amalloc_D(sizeof(RegMask) * (3*6+4));

   idealreg2spillmask  [Op_RegN] = &rms[0];

   idealreg2spillmask  [Op_RegI] = &rms[1];

   idealreg2spillmask  [Op_RegL] = &rms[2];

   idealreg2spillmask  [Op_RegF] = &rms[3];

   idealreg2spillmask  [Op_RegD] = &rms[4];

   idealreg2spillmask  [Op_RegP] = &rms[5];

   idealreg2debugmask  [Op_RegN] = &rms[6];

   idealreg2debugmask  [Op_RegI] = &rms[7];

   idealreg2debugmask  [Op_RegL] = &rms[8];

   idealreg2debugmask  [Op_RegF] = &rms[9];

   idealreg2debugmask  [Op_RegD] = &rms[10];

   idealreg2debugmask  [Op_RegP] = &rms[11];

   idealreg2mhdebugmask[Op_RegN] = &rms[12];

   idealreg2mhdebugmask[Op_RegI] = &rms[13];

   idealreg2mhdebugmask[Op_RegL] = &rms[14];

   idealreg2mhdebugmask[Op_RegF] = &rms[15];

   idealreg2mhdebugmask[Op_RegD] = &rms[16];

   idealreg2mhdebugmask[Op_RegP] = &rms[17];

   idealreg2spillmask  [Op_VecS] = &rms[18];

   idealreg2spillmask  [Op_VecD] = &rms[19];

   idealreg2spillmask  [Op_VecX] = &rms[20];

   idealreg2spillmask  [Op_VecY] = &rms[21];

   OptoReg::Name i;

   // At first, start with the empty mask

   C->FIRST_STACK_mask().Clear();

   // Add in the incoming argument area

   OptoReg::Name init = OptoReg::add(_old_SP, C->out_preserve_stack_slots());

   for (i = init; i < _in_arg_limit; i = OptoReg::add(i,1))

     C->FIRST_STACK_mask().Insert(i);

   // Add in all bits past the outgoing argument area

   guarantee(RegMask::can_represent_arg(OptoReg::add(_out_arg_limit,-1)),

             "must be able to represent all call arguments in reg mask");

   init = _out_arg_limit;

   for (i = init; RegMask::can_represent(i); i = OptoReg::add(i,1))

     C->FIRST_STACK_mask().Insert(i);

   // Finally, set the "infinite stack" bit.

   C->FIRST_STACK_mask().set_AllStack();

   // Make spill masks.  Registers for their class, plus FIRST_STACK_mask.

   RegMask aligned_stack_mask = C->FIRST_STACK_mask();

   // Keep spill masks aligned.

   aligned_stack_mask.clear_to_pairs();

   assert(aligned_stack_mask.is_AllStack(), "should be infinite stack");

   *idealreg2spillmask[Op_RegP] = *idealreg2regmask[Op_RegP];

 #ifdef _LP64

   *idealreg2spillmask[Op_RegN] = *idealreg2regmask[Op_RegN];

    idealreg2spillmask[Op_RegN]->OR(C->FIRST_STACK_mask());

    idealreg2spillmask[Op_RegP]->OR(aligned_stack_mask);

 #else

    idealreg2spillmask[Op_RegP]->OR(C->FIRST_STACK_mask());

 #endif

   *idealreg2spillmask[Op_RegI] = *idealreg2regmask[Op_RegI];

    idealreg2spillmask[Op_RegI]->OR(C->FIRST_STACK_mask());

   *idealreg2spillmask[Op_RegL] = *idealreg2regmask[Op_RegL];

    idealreg2spillmask[Op_RegL]->OR(aligned_stack_mask);

   *idealreg2spillmask[Op_RegF] = *idealreg2regmask[Op_RegF];

    idealreg2spillmask[Op_RegF]->OR(C->FIRST_STACK_mask());

   *idealreg2spillmask[Op_RegD] = *idealreg2regmask[Op_RegD];

    idealreg2spillmask[Op_RegD]->OR(aligned_stack_mask);

   if (Matcher::vector_size_supported(T_BYTE,4)) {

     *idealreg2spillmask[Op_VecS] = *idealreg2regmask[Op_VecS];

      idealreg2spillmask[Op_VecS]->OR(C->FIRST_STACK_mask());

   }

   if (Matcher::vector_size_supported(T_FLOAT,2)) {

     *idealreg2spillmask[Op_VecD] = *idealreg2regmask[Op_VecD];

      idealreg2spillmask[Op_VecD]->OR(aligned_stack_mask);

   }

   if (Matcher::vector_size_supported(T_FLOAT,4)) {

      aligned_stack_mask.clear_to_sets(RegMask::SlotsPerVecX);

      assert(aligned_stack_mask.is_AllStack(), "should be infinite stack");

     *idealreg2spillmask[Op_VecX] = *idealreg2regmask[Op_VecX];

      idealreg2spillmask[Op_VecX]->OR(aligned_stack_mask);

   }

   if (Matcher::vector_size_supported(T_FLOAT,8)) {

      aligned_stack_mask.clear_to_sets(RegMask::SlotsPerVecY);

      assert(aligned_stack_mask.is_AllStack(), "should be infinite stack");

     *idealreg2spillmask[Op_VecY] = *idealreg2regmask[Op_VecY];

      idealreg2spillmask[Op_VecY]->OR(aligned_stack_mask);

   }

    if (UseFPUForSpilling) {

      // This mask logic assumes that the spill operations are

      // symmetric and that the registers involved are the same size.

      // On sparc for instance we may have to use 64 bit moves will

      // kill 2 registers when used with F0-F31.

      idealreg2spillmask[Op_RegI]->OR(*idealreg2regmask[Op_RegF]);

      idealreg2spillmask[Op_RegF]->OR(*idealreg2regmask[Op_RegI]);

 #ifdef _LP64

      idealreg2spillmask[Op_RegN]->OR(*idealreg2regmask[Op_RegF]);

      idealreg2spillmask[Op_RegL]->OR(*idealreg2regmask[Op_RegD]);

      idealreg2spillmask[Op_RegD]->OR(*idealreg2regmask[Op_RegL]);

      idealreg2spillmask[Op_RegP]->OR(*idealreg2regmask[Op_RegD]);

 #else

      idealreg2spillmask[Op_RegP]->OR(*idealreg2regmask[Op_RegF]);

 #ifdef ARM

      // ARM has support for moving 64bit values between a pair of

      // integer registers and a double register

      idealreg2spillmask[Op_RegL]->OR(*idealreg2regmask[Op_RegD]);

      idealreg2spillmask[Op_RegD]->OR(*idealreg2regmask[Op_RegL]);

 #endif

 #endif

    }

   // Make up debug masks.  Any spill slot plus callee-save registers.

   // Caller-save registers are assumed to be trashable by the various

   // inline-cache fixup routines.

   *idealreg2debugmask  [Op_RegN]= *idealreg2spillmask[Op_RegN];

   *idealreg2debugmask  [Op_RegI]= *idealreg2spillmask[Op_RegI];

   *idealreg2debugmask  [Op_RegL]= *idealreg2spillmask[Op_RegL];

   *idealreg2debugmask  [Op_RegF]= *idealreg2spillmask[Op_RegF];

   *idealreg2debugmask  [Op_RegD]= *idealreg2spillmask[Op_RegD];

   *idealreg2debugmask  [Op_RegP]= *idealreg2spillmask[Op_RegP];

   *idealreg2mhdebugmask[Op_RegN]= *idealreg2spillmask[Op_RegN];

   *idealreg2mhdebugmask[Op_RegI]= *idealreg2spillmask[Op_RegI];

   *idealreg2mhdebugmask[Op_RegL]= *idealreg2spillmask[Op_RegL];

   *idealreg2mhdebugmask[Op_RegF]= *idealreg2spillmask[Op_RegF];

   *idealreg2mhdebugmask[Op_RegD]= *idealreg2spillmask[Op_RegD];

   *idealreg2mhdebugmask[Op_RegP]= *idealreg2spillmask[Op_RegP];

   // Prevent stub compilations from attempting to reference

   // callee-saved registers from debug info

   bool exclude_soe = !Compile::current()->is_method_compilation();

   for( i=OptoReg::Name(0); i<OptoReg::Name(_last_Mach_Reg); i = OptoReg::add(i,1) ) {

     // registers the caller has to save do not work

     if( _register_save_policy[i] == 'C' ||

         _register_save_policy[i] == 'A' ||

         (_register_save_policy[i] == 'E' && exclude_soe) ) {

       idealreg2debugmask  [Op_RegN]->Remove(i);

       idealreg2debugmask  [Op_RegI]->Remove(i); // Exclude save-on-call

       idealreg2debugmask  [Op_RegL]->Remove(i); // registers from debug

       idealreg2debugmask  [Op_RegF]->Remove(i); // masks

       idealreg2debugmask  [Op_RegD]->Remove(i);

       idealreg2debugmask  [Op_RegP]->Remove(i);

       idealreg2mhdebugmask[Op_RegN]->Remove(i);

       idealreg2mhdebugmask[Op_RegI]->Remove(i);

       idealreg2mhdebugmask[Op_RegL]->Remove(i);

       idealreg2mhdebugmask[Op_RegF]->Remove(i);

       idealreg2mhdebugmask[Op_RegD]->Remove(i);

       idealreg2mhdebugmask[Op_RegP]->Remove(i);

     }

   }

   // Subtract the register we use to save the SP for MethodHandle

   // invokes to from the debug mask.

   const RegMask save_mask = method_handle_invoke_SP_save_mask();

   idealreg2mhdebugmask[Op_RegN]->SUBTRACT(save_mask);

   idealreg2mhdebugmask[Op_RegI]->SUBTRACT(save_mask);

   idealreg2mhdebugmask[Op_RegL]->SUBTRACT(save_mask);

   idealreg2mhdebugmask[Op_RegF]->SUBTRACT(save_mask);

   idealreg2mhdebugmask[Op_RegD]->SUBTRACT(save_mask);

   idealreg2mhdebugmask[Op_RegP]->SUBTRACT(save_mask);

 }

 //---------------------------is_save_on_entry----------------------------------

 bool Matcher::is_save_on_entry( int reg ) {

   return

     _register_save_policy[reg] == 'E' ||

     _register_save_policy[reg] == 'A' || // Save-on-entry register?

     // Also save argument registers in the trampolining stubs

     (C->save_argument_registers() && is_spillable_arg(reg));

 }

 //---------------------------Fixup_Save_On_Entry-------------------------------

 void Matcher::Fixup_Save_On_Entry( ) {

   init_first_stack_mask();

   Node *root = C->root();       // Short name for root

   // Count number of save-on-entry registers.

   uint soe_cnt = number_of_saved_registers();

   uint i;

   // Find the procedure Start Node

   StartNode *start = C->start();

   assert( start, "Expect a start node" );

   // Save argument registers in the trampolining stubs

   if( C->save_argument_registers() )

     for( i = 0; i < _last_Mach_Reg; i++ )

       if( is_spillable_arg(i) )

         soe_cnt++;

   // Input RegMask array shared by all Returns.

   // The type for doubles and longs has a count of 2, but

   // there is only 1 returned value

   uint ret_edge_cnt = TypeFunc::Parms + ((C->tf()->range()->cnt() == TypeFunc::Parms) ? 0 : 1);

   RegMask *ret_rms  = init_input_masks( ret_edge_cnt + soe_cnt, _return_addr_mask, c_frame_ptr_mask );

   // Returns have 0 or 1 returned values depending on call signature.

   // Return register is specified by return_value in the AD file.

   if (ret_edge_cnt > TypeFunc::Parms)

     ret_rms[TypeFunc::Parms+0] = _return_value_mask;

   // Input RegMask array shared by all Rethrows.

   uint reth_edge_cnt = TypeFunc::Parms+1;

   RegMask *reth_rms  = init_input_masks( reth_edge_cnt + soe_cnt, _return_addr_mask, c_frame_ptr_mask );

   // Rethrow takes exception oop only, but in the argument 0 slot.

   reth_rms[TypeFunc::Parms] = mreg2regmask[find_receiver(false)];

 #ifdef _LP64

   // Need two slots for ptrs in 64-bit land

   reth_rms[TypeFunc::Parms].Insert(OptoReg::add(OptoReg::Name(find_receiver(false)),1));

 #endif

   // Input RegMask array shared by all TailCalls

   uint tail_call_edge_cnt = TypeFunc::Parms+2;

   RegMask *tail_call_rms = init_input_masks( tail_call_edge_cnt + soe_cnt, _return_addr_mask, c_frame_ptr_mask );

   // Input RegMask array shared by all TailJumps

   uint tail_jump_edge_cnt = TypeFunc::Parms+2;

   RegMask *tail_jump_rms = init_input_masks( tail_jump_edge_cnt + soe_cnt, _return_addr_mask, c_frame_ptr_mask );

   // TailCalls have 2 returned values (target & moop), whose masks come

   // from the usual MachNode/MachOper mechanism.  Find a sample

   // TailCall to extract these masks and put the correct masks into

   // the tail_call_rms array.

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

     MachReturnNode *m = root->in(i)->as_MachReturn();

     if( m->ideal_Opcode() == Op_TailCall ) {

       tail_call_rms[TypeFunc::Parms+0] = m->MachNode::in_RegMask(TypeFunc::Parms+0);

       tail_call_rms[TypeFunc::Parms+1] = m->MachNode::in_RegMask(TypeFunc::Parms+1);

       break;

     }

   }

   // TailJumps have 2 returned values (target & ex_oop), whose masks come

   // from the usual MachNode/MachOper mechanism.  Find a sample

   // TailJump to extract these masks and put the correct masks into

   // the tail_jump_rms array.

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

     MachReturnNode *m = root->in(i)->as_MachReturn();

     if( m->ideal_Opcode() == Op_TailJump ) {

       tail_jump_rms[TypeFunc::Parms+0] = m->MachNode::in_RegMask(TypeFunc::Parms+0);

       tail_jump_rms[TypeFunc::Parms+1] = m->MachNode::in_RegMask(TypeFunc::Parms+1);

       break;

     }

   }

   // Input RegMask array shared by all Halts

   uint halt_edge_cnt = TypeFunc::Parms;

   RegMask *halt_rms = init_input_masks( halt_edge_cnt + soe_cnt, _return_addr_mask, c_frame_ptr_mask );

   // Capture the return input masks into each exit flavor

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

     MachReturnNode *exit = root->in(i)->as_MachReturn();

     switch( exit->ideal_Opcode() ) {

       case Op_Return   : exit->_in_rms = ret_rms;  break;

       case Op_Rethrow  : exit->_in_rms = reth_rms; break;

       case Op_TailCall : exit->_in_rms = tail_call_rms; break;

       case Op_TailJump : exit->_in_rms = tail_jump_rms; break;

       case Op_Halt     : exit->_in_rms = halt_rms; break;

       default          : ShouldNotReachHere();

     }

   }

   // Next unused projection number from Start.

   int proj_cnt = C->tf()->domain()->cnt();

   // Do all the save-on-entry registers.  Make projections from Start for

   // them, and give them a use at the exit points.  To the allocator, they

   // look like incoming register arguments.

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

     if( is_save_on_entry(i) ) {

       // Add the save-on-entry to the mask array

       ret_rms      [      ret_edge_cnt] = mreg2regmask[i];

       reth_rms     [     reth_edge_cnt] = mreg2regmask[i];

       tail_call_rms[tail_call_edge_cnt] = mreg2regmask[i];

       tail_jump_rms[tail_jump_edge_cnt] = mreg2regmask[i];

       // Halts need the SOE registers, but only in the stack as debug info.

       // A just-prior uncommon-trap or deoptimization will use the SOE regs.

       halt_rms     [     halt_edge_cnt] = *idealreg2spillmask[_register_save_type[i]];

       Node *mproj;

       // Is this a RegF low half of a RegD?  Double up 2 adjacent RegF's

       // into a single RegD.

       if( (i&1) == 0 &&

           _register_save_type[i  ] == Op_RegF &&

           _register_save_type[i+1] == Op_RegF &&

           is_save_on_entry(i+1) ) {

         // Add other bit for double

         ret_rms      [      ret_edge_cnt].Insert(OptoReg::Name(i+1));

         reth_rms     [     reth_edge_cnt].Insert(OptoReg::Name(i+1));

         tail_call_rms[tail_call_edge_cnt].Insert(OptoReg::Name(i+1));

         tail_jump_rms[tail_jump_edge_cnt].Insert(OptoReg::Name(i+1));

         halt_rms     [     halt_edge_cnt].Insert(OptoReg::Name(i+1));

         mproj = new (C, 1) MachProjNode( start, proj_cnt, ret_rms[ret_edge_cnt], Op_RegD );

         proj_cnt += 2;          // Skip 2 for doubles

       }

       else if( (i&1) == 1 &&    // Else check for high half of double

                _register_save_type[i-1] == Op_RegF &&

                _register_save_type[i  ] == Op_RegF &&

                is_save_on_entry(i-1) ) {

         ret_rms      [      ret_edge_cnt] = RegMask::Empty;

         reth_rms     [     reth_edge_cnt] = RegMask::Empty;

         tail_call_rms[tail_call_edge_cnt] = RegMask::Empty;

         tail_jump_rms[tail_jump_edge_cnt] = RegMask::Empty;

         halt_rms     [     halt_edge_cnt] = RegMask::Empty;

         mproj = C->top();

       }

       // Is this a RegI low half of a RegL?  Double up 2 adjacent RegI's

       // into a single RegL.

       else if( (i&1) == 0 &&

           _register_save_type[i  ] == Op_RegI &&

           _register_save_type[i+1] == Op_RegI &&

         is_save_on_entry(i+1) ) {

         // Add other bit for long

         ret_rms      [      ret_edge_cnt].Insert(OptoReg::Name(i+1));

         reth_rms     [     reth_edge_cnt].Insert(OptoReg::Name(i+1));

         tail_call_rms[tail_call_edge_cnt].Insert(OptoReg::Name(i+1));

         tail_jump_rms[tail_jump_edge_cnt].Insert(OptoReg::Name(i+1));

         halt_rms     [     halt_edge_cnt].Insert(OptoReg::Name(i+1));

         mproj = new (C, 1) MachProjNode( start, proj_cnt, ret_rms[ret_edge_cnt], Op_RegL );

         proj_cnt += 2;          // Skip 2 for longs

       }

       else if( (i&1) == 1 &&    // Else check for high half of long

                _register_save_type[i-1] == Op_RegI &&

                _register_save_type[i  ] == Op_RegI &&

                is_save_on_entry(i-1) ) {

         ret_rms      [      ret_edge_cnt] = RegMask::Empty;

         reth_rms     [     reth_edge_cnt] = RegMask::Empty;

         tail_call_rms[tail_call_edge_cnt] = RegMask::Empty;

         tail_jump_rms[tail_jump_edge_cnt] = RegMask::Empty;

         halt_rms     [     halt_edge_cnt] = RegMask::Empty;

         mproj = C->top();

       } else {

         // Make a projection for it off the Start

         mproj = new (C, 1) MachProjNode( start, proj_cnt++, ret_rms[ret_edge_cnt], _register_save_type[i] );

       }

       ret_edge_cnt ++;

       reth_edge_cnt ++;

       tail_call_edge_cnt ++;

       tail_jump_edge_cnt ++;

       halt_edge_cnt ++;

       // Add a use of the SOE register to all exit paths

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

         root->in(j)->add_req(mproj);

     } // End of if a save-on-entry register

   } // End of for all machine registers

 }

 //------------------------------init_spill_mask--------------------------------

 void Matcher::init_spill_mask( Node *ret ) {

   if( idealreg2regmask[Op_RegI] ) return; // One time only init

   OptoReg::c_frame_pointer = c_frame_pointer();

   c_frame_ptr_mask = c_frame_pointer();

 #ifdef _LP64

   // pointers are twice as big

   c_frame_ptr_mask.Insert(OptoReg::add(c_frame_pointer(),1));

 #endif

   // Start at OptoReg::stack0()

   STACK_ONLY_mask.Clear();

   OptoReg::Name init = OptoReg::stack2reg(0);

   // STACK_ONLY_mask is all stack bits

   OptoReg::Name i;

   for (i = init; RegMask::can_represent(i); i = OptoReg::add(i,1))

     STACK_ONLY_mask.Insert(i);

   // Also set the "infinite stack" bit.

   STACK_ONLY_mask.set_AllStack();

   // Copy the register names over into the shared world

   for( i=OptoReg::Name(0); i<OptoReg::Name(_last_Mach_Reg); i = OptoReg::add(i,1) ) {

     // SharedInfo::regName[i] = regName[i];

     // Handy RegMasks per machine register

     mreg2regmask[i].Insert(i);

   }

   // Grab the Frame Pointer

   Node *fp  = ret->in(TypeFunc::FramePtr);

   Node *mem = ret->in(TypeFunc::Memory);

   const TypePtr* atp = TypePtr::BOTTOM;

   // Share frame pointer while making spill ops

   set_shared(fp);

   // Compute generic short-offset Loads

 #ifdef _LP64

   MachNode *spillCP = match_tree(new (C, 3) LoadNNode(NULL,mem,fp,atp,TypeInstPtr::BOTTOM));

 #endif

   MachNode *spillI  = match_tree(new (C, 3) LoadINode(NULL,mem,fp,atp));

   MachNode *spillL  = match_tree(new (C, 3) LoadLNode(NULL,mem,fp,atp));

   MachNode *spillF  = match_tree(new (C, 3) LoadFNode(NULL,mem,fp,atp));

   MachNode *spillD  = match_tree(new (C, 3) LoadDNode(NULL,mem,fp,atp));

   MachNode *spillP  = match_tree(new (C, 3) LoadPNode(NULL,mem,fp,atp,TypeInstPtr::BOTTOM));

   assert(spillI != NULL && spillL != NULL && spillF != NULL &&

          spillD != NULL && spillP != NULL, "");

   // Get the ADLC notion of the right regmask, for each basic type.

 #ifdef _LP64

   idealreg2regmask[Op_RegN] = &spillCP->out_RegMask();

 #endif

   idealreg2regmask[Op_RegI] = &spillI->out_RegMask();

   idealreg2regmask[Op_RegL] = &spillL->out_RegMask();

   idealreg2regmask[Op_RegF] = &spillF->out_RegMask();

   idealreg2regmask[Op_RegD] = &spillD->out_RegMask();

   idealreg2regmask[Op_RegP] = &spillP->out_RegMask();

   // Vector regmasks.

   if (Matcher::vector_size_supported(T_BYTE,4)) {

     TypeVect::VECTS = TypeVect::make(T_BYTE, 4);

     MachNode *spillVectS = match_tree(new (C, 3) LoadVectorNode(NULL,mem,fp,atp,TypeVect::VECTS));

     idealreg2regmask[Op_VecS] = &spillVectS->out_RegMask();

   }

   if (Matcher::vector_size_supported(T_FLOAT,2)) {

     MachNode *spillVectD = match_tree(new (C, 3) LoadVectorNode(NULL,mem,fp,atp,TypeVect::VECTD));

     idealreg2regmask[Op_VecD] = &spillVectD->out_RegMask();

   }

   if (Matcher::vector_size_supported(T_FLOAT,4)) {

     MachNode *spillVectX = match_tree(new (C, 3) LoadVectorNode(NULL,mem,fp,atp,TypeVect::VECTX));

     idealreg2regmask[Op_VecX] = &spillVectX->out_RegMask();

   }

   if (Matcher::vector_size_supported(T_FLOAT,8)) {

     MachNode *spillVectY = match_tree(new (C, 3) LoadVectorNode(NULL,mem,fp,atp,TypeVect::VECTY));

     idealreg2regmask[Op_VecY] = &spillVectY->out_RegMask();

   }

 }

 #ifdef ASSERT

 static void match_alias_type(Compile* C, Node* n, Node* m) {

   if (!VerifyAliases)  return;  // do not go looking for trouble by default

   const TypePtr* nat = n->adr_type();

   const TypePtr* mat = m->adr_type();

   int nidx = C->get_alias_index(nat);

   int midx = C->get_alias_index(mat);

   // Detune the assert for cases like (AndI 0xFF (LoadB p)).

   if (nidx == Compile::AliasIdxTop && midx >= Compile::AliasIdxRaw) {

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

       Node* n1 = n->in(i);

       const TypePtr* n1at = n1->adr_type();

       if (n1at != NULL) {

         nat = n1at;

         nidx = C->get_alias_index(n1at);

       }

     }

   }

   // %%% Kludgery.  Instead, fix ideal adr_type methods for all these cases:

   if (nidx == Compile::AliasIdxTop && midx == Compile::AliasIdxRaw) {

     switch (n->Opcode()) {

     case Op_PrefetchRead:

     case Op_PrefetchWrite:

     case Op_PrefetchAllocation:

       nidx = Compile::AliasIdxRaw;

       nat = TypeRawPtr::BOTTOM;

       break;

     }

   }

   if (nidx == Compile::AliasIdxRaw && midx == Compile::AliasIdxTop) {

     switch (n->Opcode()) {

     case Op_ClearArray:

       midx = Compile::AliasIdxRaw;

       mat = TypeRawPtr::BOTTOM;

       break;

     }

   }

   if (nidx == Compile::AliasIdxTop && midx == Compile::AliasIdxBot) {

     switch (n->Opcode()) {

     case Op_Return:

     case Op_Rethrow:

     case Op_Halt:

     case Op_TailCall:

     case Op_TailJump:

       nidx = Compile::AliasIdxBot;

       nat = TypePtr::BOTTOM;

       break;

     }

   }

   if (nidx == Compile::AliasIdxBot && midx == Compile::AliasIdxTop) {

     switch (n->Opcode()) {

     case Op_StrComp:

     case Op_StrEquals:

     case Op_StrIndexOf:

     case Op_AryEq:

     case Op_MemBarVolatile:

     case Op_MemBarCPUOrder: // %%% these ideals should have narrower adr_type?

       nidx = Compile::AliasIdxTop;

       nat = NULL;

       break;

     }

   }

   if (nidx != midx) {

     if (PrintOpto || (PrintMiscellaneous && (WizardMode || Verbose))) {

       tty->print_cr("==== Matcher alias shift %d => %d", nidx, midx);

       n->dump();

       m->dump();

     }

     assert(C->subsume_loads() && C->must_alias(nat, midx),

            "must not lose alias info when matching");

   }

 }

 #endif

 //------------------------------MStack-----------------------------------------

 // State and MStack class used in xform() and find_shared() iterative methods.

 enum Node_State { Pre_Visit,  // node has to be pre-visited

                       Visit,  // visit node

                  Post_Visit,  // post-visit node

              Alt_Post_Visit   // alternative post-visit path

                 };

 class MStack: public Node_Stack {

   public:

     MStack(int size) : Node_Stack(size) { }

     void push(Node *n, Node_State ns) {

       Node_Stack::push(n, (uint)ns);

     }

     void push(Node *n, Node_State ns, Node *parent, int indx) {

       ++_inode_top;

       if ((_inode_top + 1) >= _inode_max) grow();

       _inode_top->node = parent;

       _inode_top->indx = (uint)indx;

       ++_inode_top;

       _inode_top->node = n;

       _inode_top->indx = (uint)ns;

     }

     Node *parent() {

       pop();

       return node();

     }

     Node_State state() const {

       return (Node_State)index();

     }

     void set_state(Node_State ns) {

       set_index((uint)ns);

     }

 };

 //------------------------------xform------------------------------------------

 // Given a Node in old-space, Match him (Label/Reduce) to produce a machine

 // Node in new-space.  Given a new-space Node, recursively walk his children.

 Node *Matcher::transform( Node *n ) { ShouldNotCallThis(); return n; }

 Node *Matcher::xform( Node *n, int max_stack ) {

   // Use one stack to keep both: child's node/state and parent's node/index

   MStack mstack(max_stack * 2 * 2); // C->unique() * 2 * 2

   mstack.push(n, Visit, NULL, -1);  // set NULL as parent to indicate root

   while (mstack.is_nonempty()) {

     n = mstack.node();          // Leave node on stack

     Node_State nstate = mstack.state();

     if (nstate == Visit) {

       mstack.set_state(Post_Visit);

       Node *oldn = n;

       // Old-space or new-space check

       if (!C->node_arena()->contains(n)) {

         // Old space!

         Node* m;

         if (has_new_node(n)) {  // Not yet Label/Reduced

           m = new_node(n);

         } else {

           if (!is_dontcare(n)) { // Matcher can match this guy

             // Calls match special.  They match alone with no children.

             // Their children, the incoming arguments, match normally.

             m = n->is_SafePoint() ? match_sfpt(n->as_SafePoint()):match_tree(n);

             if (C->failing())  return NULL;

             if (m == NULL) { Matcher::soft_match_failure(); return NULL; }

           } else {                  // Nothing the matcher cares about

             if( n->is_Proj() && n->in(0)->is_Multi()) {       // Projections?

               // Convert to machine-dependent projection

               m = n->in(0)->as_Multi()->match( n->as_Proj(), this );

 #ifdef ASSERT

               _new2old_map.map(m->_idx, n);

 #endif

               if (m->in(0) != NULL) // m might be top

                 collect_null_checks(m, n);

             } else {                // Else just a regular 'ol guy

               m = n->clone();       // So just clone into new-space

 #ifdef ASSERT

               _new2old_map.map(m->_idx, n);

 #endif

               // Def-Use edges will be added incrementally as Uses

               // of this node are matched.

               assert(m->outcnt() == 0, "no Uses of this clone yet");

             }

           }

           set_new_node(n, m);       // Map old to new

           if (_old_node_note_array != NULL) {

             Node_Notes* nn = C->locate_node_notes(_old_node_note_array,

                                                   n->_idx);

             C->set_node_notes_at(m->_idx, nn);

           }

           debug_only(match_alias_type(C, n, m));

         }

         n = m;    // n is now a new-space node

         mstack.set_node(n);

       }

       // New space!

       if (_visited.test_set(n->_idx)) continue; // while(mstack.is_nonempty())

       int i;

       // Put precedence edges on stack first (match them last).

       for (i = oldn->req(); (uint)i < oldn->len(); i++) {

         Node *m = oldn->in(i);

         if (m == NULL) break;

         // set -1 to call add_prec() instead of set_req() during Step1

         mstack.push(m, Visit, n, -1);

       }

       // For constant debug info, I'd rather have unmatched constants.

       int cnt = n->req();

       JVMState* jvms = n->jvms();

       int debug_cnt = jvms ? jvms->debug_start() : cnt;

       // Now do only debug info.  Clone constants rather than matching.

       // Constants are represented directly in the debug info without

       // the need for executable machine instructions.

       // Monitor boxes are also represented directly.

       for (i = cnt - 1; i >= debug_cnt; --i) { // For all debug inputs do

         Node *m = n->in(i);          // Get input

         int op = m->Opcode();

         assert((op == Op_BoxLock) == jvms->is_monitor_use(i), "boxes only at monitor sites");

         if( op == Op_ConI || op == Op_ConP || op == Op_ConN ||

             op == Op_ConF || op == Op_ConD || op == Op_ConL

             // || op == Op_BoxLock  // %%%% enable this and remove (+++) in chaitin.cpp

             ) {

           m = m->clone();

 #ifdef ASSERT

           _new2old_map.map(m->_idx, n);

 #endif

           mstack.push(m, Post_Visit, n, i); // Don't need to visit

           mstack.push(m->in(0), Visit, m, 0);

         } else {

           mstack.push(m, Visit, n, i);

         }

       }

       // And now walk his children, and convert his inputs to new-space.

       for( ; i >= 0; --i ) { // For all normal inputs do

         Node *m = n->in(i);  // Get input

         if(m != NULL)

           mstack.push(m, Visit, n, i);

       }

     }

     else if (nstate == Post_Visit) {

       // Set xformed input

       Node *p = mstack.parent();

       if (p != NULL) { // root doesn't have parent

         int i = (int)mstack.index();

         if (i >= 0)

           p->set_req(i, n); // required input

         else if (i == -1)

           p->add_prec(n);   // precedence input

         else

           ShouldNotReachHere();

       }

       mstack.pop(); // remove processed node from stack

     }

     else {

       ShouldNotReachHere();

     }

   } // while (mstack.is_nonempty())

   return n; // Return new-space Node

 }

 //------------------------------warp_outgoing_stk_arg------------------------

 OptoReg::Name Matcher::warp_outgoing_stk_arg( VMReg reg, OptoReg::Name begin_out_arg_area, OptoReg::Name &out_arg_limit_per_call ) {

   // Convert outgoing argument location to a pre-biased stack offset

   if (reg->is_stack()) {

     OptoReg::Name warped = reg->reg2stack();

     // Adjust the stack slot offset to be the register number used

     // by the allocator.

     warped = OptoReg::add(begin_out_arg_area, warped);

     // Keep track of the largest numbered stack slot used for an arg.

     // Largest used slot per call-site indicates the amount of stack

     // that is killed by the call.

     if( warped >= out_arg_limit_per_call )

       out_arg_limit_per_call = OptoReg::add(warped,1);

     if (!RegMask::can_represent_arg(warped)) {

       C->record_method_not_compilable_all_tiers("unsupported calling sequence");

       return OptoReg::Bad;

     }

     return warped;

   }

   return OptoReg::as_OptoReg(reg);

 }

 //------------------------------match_sfpt-------------------------------------

 // Helper function to match call instructions.  Calls match special.

 // They match alone with no children.  Their children, the incoming

 // arguments, match normally.

 MachNode *Matcher::match_sfpt( SafePointNode *sfpt ) {

   MachSafePointNode *msfpt = NULL;

   MachCallNode      *mcall = NULL;

   uint               cnt;

   // Split out case for SafePoint vs Call

   CallNode *call;

   const TypeTuple *domain;

   ciMethod*        method = NULL;

   bool             is_method_handle_invoke = false;  // for special kill effects

   if( sfpt->is_Call() ) {

     call = sfpt->as_Call();

     domain = call->tf()->domain();

     cnt = domain->cnt();

     // Match just the call, nothing else

     MachNode *m = match_tree(call);

     if (C->failing())  return NULL;

     if( m == NULL ) { Matcher::soft_match_failure(); return NULL; }

     // Copy data from the Ideal SafePoint to the machine version

     mcall = m->as_MachCall();

     mcall->set_tf(         call->tf());

     mcall->set_entry_point(call->entry_point());

     mcall->set_cnt(        call->cnt());

     if( mcall->is_MachCallJava() ) {

       MachCallJavaNode *mcall_java  = mcall->as_MachCallJava();

       const CallJavaNode *call_java =  call->as_CallJava();

       method = call_java->method();

       mcall_java->_method = method;

       mcall_java->_bci = call_java->_bci;

       mcall_java->_optimized_virtual = call_java->is_optimized_virtual();

       is_method_handle_invoke = call_java->is_method_handle_invoke();

       mcall_java->_method_handle_invoke = is_method_handle_invoke;

       if (is_method_handle_invoke) {

         C->set_has_method_handle_invokes(true);

       }

       if( mcall_java->is_MachCallStaticJava() )

         mcall_java->as_MachCallStaticJava()->_name =

          call_java->as_CallStaticJava()->_name;

       if( mcall_java->is_MachCallDynamicJava() )

         mcall_java->as_MachCallDynamicJava()->_vtable_index =

          call_java->as_CallDynamicJava()->_vtable_index;

     }

     else if( mcall->is_MachCallRuntime() ) {

       mcall->as_MachCallRuntime()->_name = call->as_CallRuntime()->_name;

     }

     msfpt = mcall;

   }

   // This is a non-call safepoint

   else {

     call = NULL;

     domain = NULL;

     MachNode *mn = match_tree(sfpt);

     if (C->failing())  return NULL;

     msfpt = mn->as_MachSafePoint();

     cnt = TypeFunc::Parms;

   }

   // Advertise the correct memory effects (for anti-dependence computation).

   msfpt->set_adr_type(sfpt->adr_type());

   // Allocate a private array of RegMasks.  These RegMasks are not shared.

   msfpt->_in_rms = NEW_RESOURCE_ARRAY( RegMask, cnt );

   // Empty them all.

   memset( msfpt->_in_rms, 0, sizeof(RegMask)*cnt );

   // Do all the pre-defined non-Empty register masks

   msfpt->_in_rms[TypeFunc::ReturnAdr] = _return_addr_mask;

   msfpt->_in_rms[TypeFunc::FramePtr ] = c_frame_ptr_mask;

   // Place first outgoing argument can possibly be put.

   OptoReg::Name begin_out_arg_area = OptoReg::add(_new_SP, C->out_preserve_stack_slots());

   assert( is_even(begin_out_arg_area), "" );

   // Compute max outgoing register number per call site.

   OptoReg::Name out_arg_limit_per_call = begin_out_arg_area;

   // Calls to C may hammer extra stack slots above and beyond any arguments.

   // These are usually backing store for register arguments for varargs.

   if( call != NULL && call->is_CallRuntime() )

     out_arg_limit_per_call = OptoReg::add(out_arg_limit_per_call,C->varargs_C_out_slots_killed());

   // Do the normal argument list (parameters) register masks

   int argcnt = cnt - TypeFunc::Parms;

   if( argcnt > 0 ) {          // Skip it all if we have no args

     BasicType *sig_bt  = NEW_RESOURCE_ARRAY( BasicType, argcnt );

     VMRegPair *parm_regs = NEW_RESOURCE_ARRAY( VMRegPair, argcnt );

     int i;

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

       sig_bt[i] = domain->field_at(i+TypeFunc::Parms)->basic_type();

     }

     // V-call to pick proper calling convention

     call->calling_convention( sig_bt, parm_regs, argcnt );

 #ifdef ASSERT

     // Sanity check users' calling convention.  Really handy during

     // the initial porting effort.  Fairly expensive otherwise.

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

       if( !parm_regs[i].first()->is_valid() &&

           !parm_regs[i].second()->is_valid() ) continue;

       VMReg reg1 = parm_regs[i].first();

       VMReg reg2 = parm_regs[i].second();

       for (int j = 0; j < i; j++) {

         if( !parm_regs[j].first()->is_valid() &&

             !parm_regs[j].second()->is_valid() ) continue;

         VMReg reg3 = parm_regs[j].first();

         VMReg reg4 = parm_regs[j].second();

         if( !reg1->is_valid() ) {

           assert( !reg2->is_valid(), "valid halvsies" );

         } else if( !reg3->is_valid() ) {

           assert( !reg4->is_valid(), "valid halvsies" );

         } else {

           assert( reg1 != reg2, "calling conv. must produce distinct regs");

           assert( reg1 != reg3, "calling conv. must produce distinct regs");

           assert( reg1 != reg4, "calling conv. must produce distinct regs");

           assert( reg2 != reg3, "calling conv. must produce distinct regs");

           assert( reg2 != reg4 || !reg2->is_valid(), "calling conv. must produce distinct regs");

           assert( reg3 != reg4, "calling conv. must produce distinct regs");

         }

       }

     }

     }

 #endif

     // Visit each argument.  Compute its outgoing register mask.

     // Return results now can have 2 bits returned.

     // Compute max over all outgoing arguments both per call-site

     // and over the entire method.

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

       // Address of incoming argument mask to fill in

       RegMask *rm = &mcall->_in_rms[i+TypeFunc::Parms];

       if( !parm_regs[i].first()->is_valid() &&

           !parm_regs[i].second()->is_valid() ) {

         continue;               // Avoid Halves

       }

       // Grab first register, adjust stack slots and insert in mask.

       OptoReg::Name reg1 = warp_outgoing_stk_arg(parm_regs[i].first(), begin_out_arg_area, out_arg_limit_per_call );

       if (OptoReg::is_valid(reg1))

         rm->Insert( reg1 );

       // Grab second register (if any), adjust stack slots and insert in mask.

       OptoReg::Name reg2 = warp_outgoing_stk_arg(parm_regs[i].second(), begin_out_arg_area, out_arg_limit_per_call );

       if (OptoReg::is_valid(reg2))

         rm->Insert( reg2 );

     } // End of for all arguments

     // Compute number of stack slots needed to restore stack in case of

     // Pascal-style argument popping.

     mcall->_argsize = out_arg_limit_per_call - begin_out_arg_area;

   }

   if (is_method_handle_invoke) {

     // Kill some extra stack space in case method handles want to do

     // a little in-place argument insertion.

     // FIXME: Is this still necessary?

     int regs_per_word  = NOT_LP64(1) LP64_ONLY(2); // %%% make a global const!

     out_arg_limit_per_call += Method::extra_stack_entries() * regs_per_word;

     // Do not update mcall->_argsize because (a) the extra space is not

     // pushed as arguments and (b) _argsize is dead (not used anywhere).

   }

   // Compute the max stack slot killed by any call.  These will not be

   // available for debug info, and will be used to adjust FIRST_STACK_mask

   // after all call sites have been visited.

   if( _out_arg_limit < out_arg_limit_per_call)

     _out_arg_limit = out_arg_limit_per_call;

   if (mcall) {

     // Kill the outgoing argument area, including any non-argument holes and

     // any legacy C-killed slots.  Use Fat-Projections to do the killing.

     // Since the max-per-method covers the max-per-call-site and debug info

     // is excluded on the max-per-method basis, debug info cannot land in

     // this killed area.

     uint r_cnt = mcall->tf()->range()->cnt();

     MachProjNode *proj = new (C, 1) MachProjNode( mcall, r_cnt+10000, RegMask::Empty, MachProjNode::fat_proj );

     if (!RegMask::can_represent_arg(OptoReg::Name(out_arg_limit_per_call-1))) {

       C->record_method_not_compilable_all_tiers("unsupported outgoing calling sequence");

     } else {

       for (int i = begin_out_arg_area; i < out_arg_limit_per_call; i++)

         proj->_rout.Insert(OptoReg::Name(i));

     }

     if( proj->_rout.is_NotEmpty() )

       _proj_list.push(proj);

   }

   // Transfer the safepoint information from the call to the mcall

   // Move the JVMState list

   msfpt->set_jvms(sfpt->jvms());

   for (JVMState* jvms = msfpt->jvms(); jvms; jvms = jvms->caller()) {

     jvms->set_map(sfpt);

   }

   // Debug inputs begin just after the last incoming parameter

   assert( (mcall == NULL) || (mcall->jvms() == NULL) ||

           (mcall->jvms()->debug_start() + mcall->_jvmadj == mcall->tf()->domain()->cnt()), "" );

   // Move the OopMap

   msfpt->_oop_map = sfpt->_oop_map;

   // Registers killed by the call are set in the local scheduling pass

   // of Global Code Motion.

   return msfpt;

 }

 //---------------------------match_tree----------------------------------------

 // Match a Ideal Node DAG - turn it into a tree; Label & Reduce.  Used as part

 // of the whole-sale conversion from Ideal to Mach Nodes.  Also used for

 // making GotoNodes while building the CFG and in init_spill_mask() to identify

 // a Load's result RegMask for memoization in idealreg2regmask[]

 MachNode *Matcher::match_tree( const Node *n ) {

   assert( n->Opcode() != Op_Phi, "cannot match" );

   assert( !n->is_block_start(), "cannot match" );

   // Set the mark for all locally allocated State objects.

   // When this call returns, the _states_arena arena will be reset

   // freeing all State objects.

   ResourceMark rm( &_states_arena );

   LabelRootDepth = 0;

   // StoreNodes require their Memory input to match any LoadNodes

   Node *mem = n->is_Store() ? n->in(MemNode::Memory) : (Node*)1 ;

 #ifdef ASSERT

   Node* save_mem_node = _mem_node;

   _mem_node = n->is_Store() ? (Node*)n : NULL;

 #endif

   // State object for root node of match tree

   // Allocate it on _states_arena - stack allocation can cause stack overflow.

   State *s = new (&_states_arena) State;

   s->_kids[0] = NULL;

   s->_kids[1] = NULL;

   s->_leaf = (Node*)n;

   // Label the input tree, allocating labels from top-level arena

   Label_Root( n, s, n->in(0), mem );

   if (C->failing())  return NULL;

   // The minimum cost match for the whole tree is found at the root State

   uint mincost = max_juint;

   uint cost = max_juint;

   uint i;

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

     if( s->valid(i) &&                // valid entry and

         s->_cost[i] < cost &&         // low cost and

         s->_rule[i] >= NUM_OPERANDS ) // not an operand

       cost = s->_cost[mincost=i];

   }

   if (mincost == max_juint) {

 #ifndef PRODUCT

     tty->print("No matching rule for:");

     s->dump();

 #endif

     Matcher::soft_match_failure();

     return NULL;

   }

   // Reduce input tree based upon the state labels to machine Nodes

   MachNode *m = ReduceInst( s, s->_rule[mincost], mem );

 #ifdef ASSERT

   _old2new_map.map(n->_idx, m);

   _new2old_map.map(m->_idx, (Node*)n);

 #endif

   // Add any Matcher-ignored edges

   uint cnt = n->req();

   uint start = 1;

   if( mem != (Node*)1 ) start = MemNode::Memory+1;

   if( n->is_AddP() ) {

     assert( mem == (Node*)1, "" );

     start = AddPNode::Base+1;

   }

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

     if( !n->match_edge(i) ) {

       if( i < m->req() )

         m->ins_req( i, n->in(i) );

       else

         m->add_req( n->in(i) );

     }

   }

   debug_only( _mem_node = save_mem_node; )

   return m;

 }

 //------------------------------match_into_reg---------------------------------

 // Choose to either match this Node in a register or part of the current

 // match tree.  Return true for requiring a register and false for matching

 // as part of the current match tree.

 static bool match_into_reg( const Node *n, Node *m, Node *control, int i, bool shared ) {

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

   if (t->singleton()) {

     // Never force constants into registers.  Allow them to match as

     // constants or registers.  Copies of the same value will share

     // the same register.  See find_shared_node.

     return false;

   } else {                      // Not a constant

     // Stop recursion if they have different Controls.

     Node* m_control = m->in(0);

     // Control of load's memory can post-dominates load's control.

     // So use it since load can't float above its memory.

     Node* mem_control = (m->is_Load()) ? m->in(MemNode::Memory)->in(0) : NULL;

     if (control && m_control && control != m_control && control != mem_control) {

       // Actually, we can live with the most conservative control we

       // find, if it post-dominates the others.  This allows us to

       // pick up load/op/store trees where the load can float a little

       // above the store.

       Node *x = control;

       const uint max_scan = 6;  // Arbitrary scan cutoff

       uint j;

       for (j=0; j<max_scan; j++) {

         if (x->is_Region())     // Bail out at merge points

           return true;

         x = x->in(0);

         if (x == m_control)     // Does 'control' post-dominate

           break;                // m->in(0)?  If so, we can use it

         if (x == mem_control)   // Does 'control' post-dominate

           break;                // mem_control?  If so, we can use it

       }

       if (j == max_scan)        // No post-domination before scan end?

         return true;            // Then break the match tree up

     }

     if (m->is_DecodeN() && Matcher::narrow_oop_use_complex_address()) {

       // These are commonly used in address expressions and can

       // efficiently fold into them on X64 in some cases.

       return false;

     }

   }

   // Not forceable cloning.  If shared, put it into a register.

   return shared;

 }

 //------------------------------Instruction Selection--------------------------

 // Label method walks a "tree" of nodes, using the ADLC generated DFA to match

 // ideal nodes to machine instructions.  Trees are delimited by shared Nodes,

 // things the Matcher does not match (e.g., Memory), and things with different

 // Controls (hence forced into different blocks).  We pass in the Control

 // selected for this entire State tree.

 // The Matcher works on Trees, but an Intel add-to-memory requires a DAG: the

 // Store and the Load must have identical Memories (as well as identical

 // pointers).  Since the Matcher does not have anything for Memory (and

 // does not handle DAGs), I have to match the Memory input myself.  If the

 // Tree root is a Store, I require all Loads to have the identical memory.

 Node *Matcher::Label_Root( const Node *n, State *svec, Node *control, const Node *mem){

   // Since Label_Root is a recursive function, its possible that we might run

   // out of stack space.  See bugs 6272980 & 6227033 for more info.

   LabelRootDepth++;

   if (LabelRootDepth > MaxLabelRootDepth) {

     C->record_method_not_compilable_all_tiers("Out of stack space, increase MaxLabelRootDepth");

     return NULL;

   }

   uint care = 0;                // Edges matcher cares about

   uint cnt = n->req();

   uint i = 0;

   // Examine children for memory state

   // Can only subsume a child into your match-tree if that child's memory state

   // is not modified along the path to another input.

   // It is unsafe even if the other inputs are separate roots.

   Node *input_mem = NULL;

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

     if( !n->match_edge(i) ) continue;

     Node *m = n->in(i);         // Get ith input

     assert( m, "expect non-null children" );

     if( m->is_Load() ) {

       if( input_mem == NULL ) {

         input_mem = m->in(MemNode::Memory);

       } else if( input_mem != m->in(MemNode::Memory) ) {

         input_mem = NodeSentinel;

       }

     }

   }

   for( i = 1; i < cnt; i++ ){// For my children

     if( !n->match_edge(i) ) continue;

     Node *m = n->in(i);         // Get ith input

     // Allocate states out of a private arena

     State *s = new (&_states_arena) State;

     svec->_kids[care++] = s;

     assert( care <= 2, "binary only for now" );

     // Recursively label the State tree.

     s->_kids[0] = NULL;

     s->_kids[1] = NULL;

     s->_leaf = m;

     // Check for leaves of the State Tree; things that cannot be a part of

     // the current tree.  If it finds any, that value is matched as a

     // register operand.  If not, then the normal matching is used.

     if( match_into_reg(n, m, control, i, is_shared(m)) ||

         //

         // Stop recursion if this is LoadNode and the root of this tree is a

         // StoreNode and the load & store have different memories.

         ((mem!=(Node*)1) && m->is_Load() && m->in(MemNode::Memory) != mem) ||

         // Can NOT include the match of a subtree when its memory state

         // is used by any of the other subtrees

         (input_mem == NodeSentinel) ) {

 #ifndef PRODUCT

       // Print when we exclude matching due to different memory states at input-loads

       if( PrintOpto && (Verbose && WizardMode) && (input_mem == NodeSentinel)

         && !((mem!=(Node*)1) && m->is_Load() && m->in(MemNode::Memory) != mem) ) {

         tty->print_cr("invalid input_mem");

       }

 #endif

       // Switch to a register-only opcode; this value must be in a register

       // and cannot be subsumed as part of a larger instruction.

       s->DFA( m->ideal_reg(), m );

     } else {

       // If match tree has no control and we do, adopt it for entire tree

       if( control == NULL && m->in(0) != NULL && m->req() > 1 )

         control = m->in(0);         // Pick up control

       // Else match as a normal part of the match tree.

       control = Label_Root(m,s,control,mem);

       if (C->failing()) return NULL;

     }

   }

   // Call DFA to match this node, and return

   svec->DFA( n->Opcode(), n );

 #ifdef ASSERT

   uint x;

   for( x = 0; x < _LAST_MACH_OPER; x++ )

     if( svec->valid(x) )

       break;

   if (x >= _LAST_MACH_OPER) {

     n->dump();

     svec->dump();

     assert( false, "bad AD file" );

   }

 #endif

   return control;

 }

 // Con nodes reduced using the same rule can share their MachNode

 // which reduces the number of copies of a constant in the final

 // program.  The register allocator is free to split uses later to

 // split live ranges.

 MachNode* Matcher::find_shared_node(Node* leaf, uint rule) {

   if (!leaf->is_Con() && !leaf->is_DecodeN()) return NULL;

   // See if this Con has already been reduced using this rule.

   if (_shared_nodes.Size() <= leaf->_idx) return NULL;

   MachNode* last = (MachNode*)_shared_nodes.at(leaf->_idx);

   if (last != NULL && rule == last->rule()) {

     // Don't expect control change for DecodeN

     if (leaf->is_DecodeN())

       return last;

     // Get the new space root.

     Node* xroot = new_node(C->root());

     if (xroot == NULL) {

       // This shouldn't happen give the order of matching.

       return NULL;

     }

     // Shared constants need to have their control be root so they

     // can be scheduled properly.

     Node* control = last->in(0);

     if (control != xroot) {

       if (control == NULL || control == C->root()) {

         last->set_req(0, xroot);

       } else {

         assert(false, "unexpected control");

         return NULL;

       }

     }

     return last;

   }

   return NULL;

 }

 //------------------------------ReduceInst-------------------------------------

 // Reduce a State tree (with given Control) into a tree of MachNodes.

 // This routine (and it's cohort ReduceOper) convert Ideal Nodes into

 // complicated machine Nodes.  Each MachNode covers some tree of Ideal Nodes.

 // Each MachNode has a number of complicated MachOper operands; each

 // MachOper also covers a further tree of Ideal Nodes.

 // The root of the Ideal match tree is always an instruction, so we enter

 // the recursion here.  After building the MachNode, we need to recurse

 // the tree checking for these cases:

 // (1) Child is an instruction -

 //     Build the instruction (recursively), add it as an edge.

 //     Build a simple operand (register) to hold the result of the instruction.

 // (2) Child is an interior part of an instruction -

 //     Skip over it (do nothing)

 // (3) Child is the start of a operand -

 //     Build the operand, place it inside the instruction

 //     Call ReduceOper.

 MachNode *Matcher::ReduceInst( State *s, int rule, Node *&mem ) {

   assert( rule >= NUM_OPERANDS, "called with operand rule" );

   MachNode* shared_node = find_shared_node(s->_leaf, rule);

   if (shared_node != NULL) {

     return shared_node;

   }

   // Build the object to represent this state & prepare for recursive calls

   MachNode *mach = s->MachNodeGenerator( rule, C );

   mach->_opnds[0] = s->MachOperGenerator( _reduceOp[rule], C );

   assert( mach->_opnds[0] != NULL, "Missing result operand" );

   Node *leaf = s->_leaf;

   // Check for instruction or instruction chain rule

   if( rule >= _END_INST_CHAIN_RULE || rule < _BEGIN_INST_CHAIN_RULE ) {

     assert(C->node_arena()->contains(s->_leaf) || !has_new_node(s->_leaf),

            "duplicating node that's already been matched");

     // Instruction

     mach->add_req( leaf->in(0) ); // Set initial control

     // Reduce interior of complex instruction

     ReduceInst_Interior( s, rule, mem, mach, 1 );

   } else {

     // Instruction chain rules are data-dependent on their inputs

     mach->add_req(0);             // Set initial control to none

     ReduceInst_Chain_Rule( s, rule, mem, mach );

   }

   // If a Memory was used, insert a Memory edge

   if( mem != (Node*)1 ) {

     mach->ins_req(MemNode::Memory,mem);

 #ifdef ASSERT

     // Verify adr type after matching memory operation

     const MachOper* oper = mach->memory_operand();

     if (oper != NULL && oper != (MachOper*)-1) {

       // It has a unique memory operand.  Find corresponding ideal mem node.

       Node* m = NULL;

       if (leaf->is_Mem()) {

         m = leaf;

       } else {

         m = _mem_node;

         assert(m != NULL && m->is_Mem(), "expecting memory node");

       }

       const Type* mach_at = mach->adr_type();

       // DecodeN node consumed by an address may have different type

       // then its input. Don't compare types for such case.

       if (m->adr_type() != mach_at &&

           (m->in(MemNode::Address)->is_DecodeN() ||

            m->in(MemNode::Address)->is_AddP() &&

            m->in(MemNode::Address)->in(AddPNode::Address)->is_DecodeN() ||

            m->in(MemNode::Address)->is_AddP() &&

            m->in(MemNode::Address)->in(AddPNode::Address)->is_AddP() &&

            m->in(MemNode::Address)->in(AddPNode::Address)->in(AddPNode::Address)->is_DecodeN())) {

         mach_at = m->adr_type();

       }

       if (m->adr_type() != mach_at) {

         m->dump();

         tty->print_cr("mach:");

         mach->dump(1);

       }

       assert(m->adr_type() == mach_at, "matcher should not change adr type");

     }

 #endif

   }

   // If the _leaf is an AddP, insert the base edge

   if( leaf->is_AddP() )

     mach->ins_req(AddPNode::Base,leaf->in(AddPNode::Base));

   uint num_proj = _proj_list.size();

   // Perform any 1-to-many expansions required

   MachNode *ex = mach->Expand(s,_proj_list, mem);

   if( ex != mach ) {

     assert(ex->ideal_reg() == mach->ideal_reg(), "ideal types should match");

     if( ex->in(1)->is_Con() )

       ex->in(1)->set_req(0, C->root());

     // Remove old node from the graph

     for( uint i=0; i<mach->req(); i++ ) {

       mach->set_req(i,NULL);

     }

 #ifdef ASSERT

     _new2old_map.map(ex->_idx, s->_leaf);

 #endif

   }

   // PhaseChaitin::fixup_spills will sometimes generate spill code

   // via the matcher.  By the time, nodes have been wired into the CFG,

   // and any further nodes generated by expand rules will be left hanging

   // in space, and will not get emitted as output code.  Catch this.

   // Also, catch any new register allocation constraints ("projections")

   // generated belatedly during spill code generation.

   if (_allocation_started) {

     guarantee(ex == mach, "no expand rules during spill generation");

     guarantee(_proj_list.size() == num_proj, "no allocation during spill generation");

   }

   if (leaf->is_Con() || leaf->is_DecodeN()) {

     // Record the con for sharing

     _shared_nodes.map(leaf->_idx, ex);

   }

   return ex;

 }

 void Matcher::ReduceInst_Chain_Rule( State *s, int rule, Node *&mem, MachNode *mach ) {

   // 'op' is what I am expecting to receive

   int op = _leftOp[rule];

   // Operand type to catch childs result

   // This is what my child will give me.

   int opnd_class_instance = s->_rule[op];

   // Choose between operand class or not.

   // This is what I will receive.

   int catch_op = (FIRST_OPERAND_CLASS <= op && op < NUM_OPERANDS) ? opnd_class_instance : op;

   // New rule for child.  Chase operand classes to get the actual rule.

   int newrule = s->_rule[catch_op];

   if( newrule < NUM_OPERANDS ) {

     // Chain from operand or operand class, may be output of shared node

     assert( 0 <= opnd_class_instance && opnd_class_instance < NUM_OPERANDS,

             "Bad AD file: Instruction chain rule must chain from operand");

     // Insert operand into array of operands for this instruction

     mach->_opnds[1] = s->MachOperGenerator( opnd_class_instance, C );

     ReduceOper( s, newrule, mem, mach );

   } else {

     // Chain from the result of an instruction

     assert( newrule >= _LAST_MACH_OPER, "Do NOT chain from internal operand");

     mach->_opnds[1] = s->MachOperGenerator( _reduceOp[catch_op], C );

     Node *mem1 = (Node*)1;

     debug_only(Node *save_mem_node = _mem_node;)

     mach->add_req( ReduceInst(s, newrule, mem1) );

     debug_only(_mem_node = save_mem_node;)

   }

   return;

 }

 uint Matcher::ReduceInst_Interior( State *s, int rule, Node *&mem, MachNode *mach, uint num_opnds ) {

   if( s->_leaf->is_Load() ) {

     Node *mem2 = s->_leaf->in(MemNode::Memory);

     assert( mem == (Node*)1 || mem == mem2, "multiple Memories being matched at once?" );

     debug_only( if( mem == (Node*)1 ) _mem_node = s->_leaf;)

     mem = mem2;

   }

   if( s->_leaf->in(0) != NULL && s->_leaf->req() > 1) {

     if( mach->in(0) == NULL )

       mach->set_req(0, s->_leaf->in(0));

   }

   // Now recursively walk the state tree & add operand list.

   for( uint i=0; i<2; i++ ) {   // binary tree

     State *newstate = s->_kids[i];

     if( newstate == NULL ) break;      // Might only have 1 child

     // 'op' is what I am expecting to receive

     int op;

     if( i == 0 ) {

       op = _leftOp[rule];

     } else {

       op = _rightOp[rule];

     }

     // Operand type to catch childs result

     // This is what my child will give me.

     int opnd_class_instance = newstate->_rule[op];

     // Choose between operand class or not.

     // This is what I will receive.

     int catch_op = (op >= FIRST_OPERAND_CLASS && op < NUM_OPERANDS) ? opnd_class_instance : op;

     // New rule for child.  Chase operand classes to get the actual rule.

     int newrule = newstate->_rule[catch_op];

     if( newrule < NUM_OPERANDS ) { // Operand/operandClass or internalOp/instruction?

       // Operand/operandClass

       // Insert operand into array of operands for this instruction

       mach->_opnds[num_opnds++] = newstate->MachOperGenerator( opnd_class_instance, C );

       ReduceOper( newstate, newrule, mem, mach );

     } else {                    // Child is internal operand or new instruction

       if( newrule < _LAST_MACH_OPER ) { // internal operand or instruction?

         // internal operand --> call ReduceInst_Interior

         // Interior of complex instruction.  Do nothing but recurse.

         num_opnds = ReduceInst_Interior( newstate, newrule, mem, mach, num_opnds );

       } else {

         // instruction --> call build operand(  ) to catch result

         //             --> ReduceInst( newrule )

         mach->_opnds[num_opnds++] = s->MachOperGenerator( _reduceOp[catch_op], C );

         Node *mem1 = (Node*)1;

         debug_only(Node *save_mem_node = _mem_node;)

         mach->add_req( ReduceInst( newstate, newrule, mem1 ) );

         debug_only(_mem_node = save_mem_node;)

       }

     }

     assert( mach->_opnds[num_opnds-1], "" );

   }

   return num_opnds;

 }

 // This routine walks the interior of possible complex operands.

 // At each point we check our children in the match tree:

 // (1) No children -

 //     We are a leaf; add _leaf field as an input to the MachNode

 // (2) Child is an internal operand -

 //     Skip over it ( do nothing )

 // (3) Child is an instruction -

 //     Call ReduceInst recursively and

 //     and instruction as an input to the MachNode

 void Matcher::ReduceOper( State *s, int rule, Node *&mem, MachNode *mach ) {

   assert( rule < _LAST_MACH_OPER, "called with operand rule" );

   State *kid = s->_kids[0];

   assert( kid == NULL || s->_leaf->in(0) == NULL, "internal operands have no control" );

   // Leaf?  And not subsumed?

   if( kid == NULL && !_swallowed[rule] ) {

     mach->add_req( s->_leaf );  // Add leaf pointer

     return;                     // Bail out

   }

   if( s->_leaf->is_Load() ) {

     assert( mem == (Node*)1, "multiple Memories being matched at once?" );

     mem = s->_leaf->in(MemNode::Memory);

     debug_only(_mem_node = s->_leaf;)

   }

   if( s->_leaf->in(0) && s->_leaf->req() > 1) {

     if( !mach->in(0) )

       mach->set_req(0,s->_leaf->in(0));

     else {

       assert( s->_leaf->in(0) == mach->in(0), "same instruction, differing controls?" );

     }

   }

   for( uint i=0; kid != NULL && i<2; kid = s->_kids[1], i++ ) {   // binary tree

     int newrule;

     if( i == 0 )

       newrule = kid->_rule[_leftOp[rule]];

     else

       newrule = kid->_rule[_rightOp[rule]];

     if( newrule < _LAST_MACH_OPER ) { // Operand or instruction?

       // Internal operand; recurse but do nothing else

       ReduceOper( kid, newrule, mem, mach );

     } else {                    // Child is a new instruction

       // Reduce the instruction, and add a direct pointer from this

       // machine instruction to the newly reduced one.

       Node *mem1 = (Node*)1;

       debug_only(Node *save_mem_node = _mem_node;)

       mach->add_req( ReduceInst( kid, newrule, mem1 ) );

       debug_only(_mem_node = save_mem_node;)

     }

   }

 }

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

 // Java-Java calling convention

 // (what you use when Java calls Java)

 //------------------------------find_receiver----------------------------------

 // For a given signature, return the OptoReg for parameter 0.

 OptoReg::Name Matcher::find_receiver( bool is_outgoing ) {

   VMRegPair regs;

   BasicType sig_bt = T_OBJECT;

   calling_convention(&sig_bt, &regs, 1, is_outgoing);

   // Return argument 0 register.  In the LP64 build pointers

   // take 2 registers, but the VM wants only the 'main' name.

   return OptoReg::as_OptoReg(regs.first());

 }

 // A method-klass-holder may be passed in the inline_cache_reg

 // and then expanded into the inline_cache_reg and a method_oop register

 //   defined in ad_<arch>.cpp

 //------------------------------find_shared------------------------------------

 // Set bits if Node is shared or otherwise a root

 void Matcher::find_shared( Node *n ) {

   // Allocate stack of size C->unique() * 2 to avoid frequent realloc

   MStack mstack(C->unique() * 2);

   // Mark nodes as address_visited if they are inputs to an address expression

   VectorSet address_visited(Thread::current()->resource_area());

   mstack.push(n, Visit);     // Don't need to pre-visit root node

   while (mstack.is_nonempty()) {

     n = mstack.node();       // Leave node on stack

     Node_State nstate = mstack.state();

     uint nop = n->Opcode();

     if (nstate == Pre_Visit) {

       if (address_visited.test(n->_idx)) { // Visited in address already?

         // Flag as visited and shared now.

         set_visited(n);

       }

       if (is_visited(n)) {   // Visited already?

         // Node is shared and has no reason to clone.  Flag it as shared.

         // This causes it to match into a register for the sharing.

         set_shared(n);       // Flag as shared and

         mstack.pop();        // remove node from stack

         continue;

       }

       nstate = Visit; // Not already visited; so visit now

     }

     if (nstate == Visit) {

       mstack.set_state(Post_Visit);

       set_visited(n);   // Flag as visited now

       bool mem_op = false;

       switch( nop ) {  // Handle some opcodes special

       case Op_Phi:             // Treat Phis as shared roots

       case Op_Parm:

       case Op_Proj:            // All handled specially during matching

       case Op_SafePointScalarObject:

         set_shared(n);

         set_dontcare(n);

         break;

       case Op_If:

       case Op_CountedLoopEnd:

         mstack.set_state(Alt_Post_Visit); // Alternative way

         // Convert (If (Bool (CmpX A B))) into (If (Bool) (CmpX A B)).  Helps

         // with matching cmp/branch in 1 instruction.  The Matcher needs the

         // Bool and CmpX side-by-side, because it can only get at constants

         // that are at the leaves of Match trees, and the Bool's condition acts

         // as a constant here.

         mstack.push(n->in(1), Visit);         // Clone the Bool

         mstack.push(n->in(0), Pre_Visit);     // Visit control input

         continue; // while (mstack.is_nonempty())

       case Op_ConvI2D:         // These forms efficiently match with a prior

       case Op_ConvI2F:         //   Load but not a following Store

         if( n->in(1)->is_Load() &&        // Prior load

             n->outcnt() == 1 &&           // Not already shared

             n->unique_out()->is_Store() ) // Following store

           set_shared(n);       // Force it to be a root

         break;

       case Op_ReverseBytesI:

       case Op_ReverseBytesL:

         if( n->in(1)->is_Load() &&        // Prior load

             n->outcnt() == 1 )            // Not already shared

           set_shared(n);                  // Force it to be a root

         break;

       case Op_BoxLock:         // Cant match until we get stack-regs in ADLC

       case Op_IfFalse:

       case Op_IfTrue:

       case Op_MachProj:

       case Op_MergeMem:

       case Op_Catch:

       case Op_CatchProj:

       case Op_CProj:

       case Op_JumpProj:

       case Op_JProj:

       case Op_NeverBranch:

         set_dontcare(n);

         break;

       case Op_Jump:

         mstack.push(n->in(1), Pre_Visit);     // Switch Value (could be shared)

         mstack.push(n->in(0), Pre_Visit);     // Visit Control input

         continue;                             // while (mstack.is_nonempty())

       case Op_StrComp:

       case Op_StrEquals:

       case Op_StrIndexOf:

       case Op_AryEq:

         set_shared(n); // Force result into register (it will be anyways)

         break;

       case Op_ConP: {  // Convert pointers above the centerline to NUL

         TypeNode *tn = n->as_Type(); // Constants derive from type nodes

         const TypePtr* tp = tn->type()->is_ptr();

         if (tp->_ptr == TypePtr::AnyNull) {

           tn->set_type(TypePtr::NULL_PTR);

         }

         break;

       }

       case Op_ConN: {  // Convert narrow pointers above the centerline to NUL

         TypeNode *tn = n->as_Type(); // Constants derive from type nodes

         const TypePtr* tp = tn->type()->make_ptr();

         if (tp && tp->_ptr == TypePtr::AnyNull) {

           tn->set_type(TypeNarrowOop::NULL_PTR);

         }

         break;

       }

       case Op_Binary:         // These are introduced in the Post_Visit state.

         ShouldNotReachHere();

         break;

       case Op_ClearArray:

       case Op_SafePoint:

         mem_op = true;

         break;

       default:

         if( n->is_Store() ) {

           // Do match stores, despite no ideal reg

           mem_op = true;

           break;

         }

         if( n->is_Mem() ) { // Loads and LoadStores

           mem_op = true;

           // Loads must be root of match tree due to prior load conflict

           if( C->subsume_loads() == false )

             set_shared(n);

         }

         // Fall into default case

         if( !n->ideal_reg() )

           set_dontcare(n);  // Unmatchable Nodes

       } // end_switch

       for(int i = n->req() - 1; i >= 0; --i) { // For my children

         Node *m = n->in(i); // Get ith input

         if (m == NULL) continue;  // Ignore NULLs

         uint mop = m->Opcode();

         // Must clone all producers of flags, or we will not match correctly.

         // Suppose a compare setting int-flags is shared (e.g., a switch-tree)

         // then it will match into an ideal Op_RegFlags.  Alas, the fp-flags

         // are also there, so we may match a float-branch to int-flags and

         // expect the allocator to haul the flags from the int-side to the

         // fp-side.  No can do.

         if( _must_clone[mop] ) {

           mstack.push(m, Visit);

           continue; // for(int i = ...)

         }

         if( mop == Op_AddP && m->in(AddPNode::Base)->Opcode() == Op_DecodeN ) {

           // Bases used in addresses must be shared but since

           // they are shared through a DecodeN they may appear

           // to have a single use so force sharing here.

           set_shared(m->in(AddPNode::Base)->in(1));

         }

         // Clone addressing expressions as they are "free" in memory access instructions

         if( mem_op && i == MemNode::Address && mop == Op_AddP ) {

           // Some inputs for address expression are not put on stack

           // to avoid marking them as shared and forcing them into register

           // if they are used only in address expressions.

           // But they should be marked as shared if there are other uses

           // besides address expressions.

           Node *off = m->in(AddPNode::Offset);

           if( off->is_Con() &&

               // When there are other uses besides address expressions

               // put it on stack and mark as shared.

               !is_visited(m) ) {

             address_visited.test_set(m->_idx); // Flag as address_visited

             Node *adr = m->in(AddPNode::Address);

             // Intel, ARM and friends can handle 2 adds in addressing mode

             if( clone_shift_expressions && adr->is_AddP() &&

                 // AtomicAdd is not an addressing expression.

                 // Cheap to find it by looking for screwy base.

                 !adr->in(AddPNode::Base)->is_top() &&

                 // Are there other uses besides address expressions?

                 !is_visited(adr) ) {

               address_visited.set(adr->_idx); // Flag as address_visited

               Node *shift = adr->in(AddPNode::Offset);

               // Check for shift by small constant as well

               if( shift->Opcode() == Op_LShiftX && shift->in(2)->is_Con() &&

                   shift->in(2)->get_int() <= 3 &&

                   // Are there other uses besides address expressions?

                   !is_visited(shift) ) {

                 address_visited.set(shift->_idx); // Flag as address_visited

                 mstack.push(shift->in(2), Visit);

                 Node *conv = shift->in(1);

 #ifdef _LP64

                 // Allow Matcher to match the rule which bypass

                 // ConvI2L operation for an array index on LP64

                 // if the index value is positive.

                 if( conv->Opcode() == Op_ConvI2L &&

                     conv->as_Type()->type()->is_long()->_lo >= 0 &&

                     // Are there other uses besides address expressions?

                     !is_visited(conv) ) {

                   address_visited.set(conv->_idx); // Flag as address_visited

                   mstack.push(conv->in(1), Pre_Visit);

                 } else

 #endif

                 mstack.push(conv, Pre_Visit);

               } else {

                 mstack.push(shift, Pre_Visit);

               }

               mstack.push(adr->in(AddPNode::Address), Pre_Visit);

               mstack.push(adr->in(AddPNode::Base), Pre_Visit);

             } else {  // Sparc, Alpha, PPC and friends

               mstack.push(adr, Pre_Visit);

             }

             // Clone X+offset as it also folds into most addressing expressions

             mstack.push(off, Visit);

             mstack.push(m->in(AddPNode::Base), Pre_Visit);

             continue; // for(int i = ...)

           } // if( off->is_Con() )

         }   // if( mem_op &&

         mstack.push(m, Pre_Visit);

       }     // for(int i = ...)

     }

     else if (nstate == Alt_Post_Visit) {

       mstack.pop(); // Remove node from stack

       // We cannot remove the Cmp input from the Bool here, as the Bool may be

       // shared and all users of the Bool need to move the Cmp in parallel.

       // This leaves both the Bool and the If pointing at the Cmp.  To

       // prevent the Matcher from trying to Match the Cmp along both paths

       // BoolNode::match_edge always returns a zero.

       // We reorder the Op_If in a pre-order manner, so we can visit without

       // accidentally sharing the Cmp (the Bool and the If make 2 users).

       n->add_req( n->in(1)->in(1) ); // Add the Cmp next to the Bool

     }

     else if (nstate == Post_Visit) {

       mstack.pop(); // Remove node from stack

       // Now hack a few special opcodes

       switch( n->Opcode() ) {       // Handle some opcodes special

       case Op_StorePConditional:

       case Op_StoreIConditional:

       case Op_StoreLConditional:

       case Op_CompareAndSwapI:

       case Op_CompareAndSwapL:

       case Op_CompareAndSwapP:

       case Op_CompareAndSwapN: {   // Convert trinary to binary-tree

         Node *newval = n->in(MemNode::ValueIn );

         Node *oldval  = n->in(LoadStoreNode::ExpectedIn);

         Node *pair = new (C, 3) BinaryNode( oldval, newval );

         n->set_req(MemNode::ValueIn,pair);

         n->del_req(LoadStoreNode::ExpectedIn);

         break;

       }

       case Op_CMoveD:              // Convert trinary to binary-tree

       case Op_CMoveF:

       case Op_CMoveI:

       case Op_CMoveL:

       case Op_CMoveN:

       case Op_CMoveP: {

         // Restructure into a binary tree for Matching.  It's possible that

         // we could move this code up next to the graph reshaping for IfNodes

         // or vice-versa, but I do not want to debug this for Ladybird.

         // 10/2/2000 CNC.

         Node *pair1 = new (C, 3) BinaryNode(n->in(1),n->in(1)->in(1));

         n->set_req(1,pair1);

         Node *pair2 = new (C, 3) BinaryNode(n->in(2),n->in(3));

         n->set_req(2,pair2);

         n->del_req(3);

         break;

       }

       case Op_LoopLimit: {

         Node *pair1 = new (C, 3) BinaryNode(n->in(1),n->in(2));

         n->set_req(1,pair1);

         n->set_req(2,n->in(3));

         n->del_req(3);

         break;

       }

       case Op_StrEquals: {

         Node *pair1 = new (C, 3) BinaryNode(n->in(2),n->in(3));

         n->set_req(2,pair1);

         n->set_req(3,n->in(4));

         n->del_req(4);

         break;

       }

       case Op_StrComp:

       case Op_StrIndexOf: {

         Node *pair1 = new (C, 3) BinaryNode(n->in(2),n->in(3));

         n->set_req(2,pair1);

         Node *pair2 = new (C, 3) BinaryNode(n->in(4),n->in(5));

         n->set_req(3,pair2);

         n->del_req(5);

         n->del_req(4);

         break;

       }

       default:

         break;

       }

     }

     else {

       ShouldNotReachHere();

     }

   } // end of while (mstack.is_nonempty())

 }

 #ifdef ASSERT

 // machine-independent root to machine-dependent root

 void Matcher::dump_old2new_map() {

   _old2new_map.dump();

 }

 #endif

 //---------------------------collect_null_checks-------------------------------

 // Find null checks in the ideal graph; write a machine-specific node for

 // it.  Used by later implicit-null-check handling.  Actually collects

 // either an IfTrue or IfFalse for the common NOT-null path, AND the ideal

 // value being tested.

 void Matcher::collect_null_checks( Node *proj, Node *orig_proj ) {

   Node *iff = proj->in(0);

   if( iff->Opcode() == Op_If ) {

     // During matching If's have Bool & Cmp side-by-side

     BoolNode *b = iff->in(1)->as_Bool();

     Node *cmp = iff->in(2);

     int opc = cmp->Opcode();

     if (opc != Op_CmpP && opc != Op_CmpN) return;

     const Type* ct = cmp->in(2)->bottom_type();

     if (ct == TypePtr::NULL_PTR ||

         (opc == Op_CmpN && ct == TypeNarrowOop::NULL_PTR)) {

       bool push_it = false;

       if( proj->Opcode() == Op_IfTrue ) {

         extern int all_null_checks_found;

         all_null_checks_found++;

         if( b->_test._test == BoolTest::ne ) {

           push_it = true;

         }

       } else {

         assert( proj->Opcode() == Op_IfFalse, "" );

         if( b->_test._test == BoolTest::eq ) {

           push_it = true;

         }

       }

       if( push_it ) {

         _null_check_tests.push(proj);

         Node* val = cmp->in(1);

 #ifdef _LP64

         if (val->bottom_type()->isa_narrowoop() &&

             !Matcher::narrow_oop_use_complex_address()) {

           //

           // Look for DecodeN node which should be pinned to orig_proj.

           // On platforms (Sparc) which can not handle 2 adds

           // in addressing mode we have to keep a DecodeN node and

           // use it to do implicit NULL check in address.

           //

           // DecodeN node was pinned to non-null path (orig_proj) during

           // CastPP transformation in final_graph_reshaping_impl().

           //

           uint cnt = orig_proj->outcnt();

           for (uint i = 0; i < orig_proj->outcnt(); i++) {

             Node* d = orig_proj->raw_out(i);

             if (d->is_DecodeN() && d->in(1) == val) {

               val = d;

               val->set_req(0, NULL); // Unpin now.

               // Mark this as special case to distinguish from

               // a regular case: CmpP(DecodeN, NULL).

               val = (Node*)(((intptr_t)val) | 1);

               break;

             }

           }

         }

 #endif

         _null_check_tests.push(val);

       }

     }

   }

 }

 //---------------------------validate_null_checks------------------------------

 // Its possible that the value being NULL checked is not the root of a match

 // tree.  If so, I cannot use the value in an implicit null check.

 void Matcher::validate_null_checks( ) {

   uint cnt = _null_check_tests.size();

   for( uint i=0; i < cnt; i+=2 ) {

     Node *test = _null_check_tests[i];

     Node *val = _null_check_tests[i+1];

     bool is_decoden = ((intptr_t)val) & 1;

     val = (Node*)(((intptr_t)val) & ~1);

     if (has_new_node(val)) {

       Node* new_val = new_node(val);

       if (is_decoden) {

         assert(val->is_DecodeN() && val->in(0) == NULL, "sanity");

         // Note: new_val may have a control edge if

         // the original ideal node DecodeN was matched before

         // it was unpinned in Matcher::collect_null_checks().

         // Unpin the mach node and mark it.

         new_val->set_req(0, NULL);

         new_val = (Node*)(((intptr_t)new_val) | 1);

       }

       // Is a match-tree root, so replace with the matched value

       _null_check_tests.map(i+1, new_val);

     } else {

       // Yank from candidate list

       _null_check_tests.map(i+1,_null_check_tests[--cnt]);

       _null_check_tests.map(i,_null_check_tests[--cnt]);

       _null_check_tests.pop();

       _null_check_tests.pop();

       i-=2;

     }

   }

 }

 // Used by the DFA in dfa_xxx.cpp.  Check for a following barrier or

 // atomic instruction acting as a store_load barrier without any

 // intervening volatile load, and thus we don't need a barrier here.

 // We retain the Node to act as a compiler ordering barrier.

 bool Matcher::post_store_load_barrier(const Node *vmb) {

   Compile *C = Compile::current();

   assert( vmb->is_MemBar(), "" );

   assert( vmb->Opcode() != Op_MemBarAcquire, "" );

   const MemBarNode *mem = (const MemBarNode*)vmb;

   // Get the Proj node, ctrl, that can be used to iterate forward

   Node *ctrl = NULL;

   DUIterator_Fast imax, i = mem->fast_outs(imax);

   while( true ) {

     ctrl = mem->fast_out(i);            // Throw out-of-bounds if proj not found

     assert( ctrl->is_Proj(), "only projections here" );

     ProjNode *proj = (ProjNode*)ctrl;

     if( proj->_con == TypeFunc::Control &&

         !C->node_arena()->contains(ctrl) ) // Unmatched old-space only

       break;

     i++;

   }

   for( DUIterator_Fast jmax, j = ctrl->fast_outs(jmax); j < jmax; j++ ) {

     Node *x = ctrl->fast_out(j);

     int xop = x->Opcode();

     // We don't need current barrier if we see another or a lock

     // before seeing volatile load.

     //

     // Op_Fastunlock previously appeared in the Op_* list below.

     // With the advent of 1-0 lock operations we're no longer guaranteed

     // that a monitor exit operation contains a serializing instruction.

     if (xop == Op_MemBarVolatile ||

         xop == Op_FastLock ||

         xop == Op_CompareAndSwapL ||

         xop == Op_CompareAndSwapP ||

         xop == Op_CompareAndSwapN ||

         xop == Op_CompareAndSwapI)

       return true;

     if (x->is_MemBar()) {

       // We must retain this membar if there is an upcoming volatile

       // load, which will be preceded by acquire membar.

       if (xop == Op_MemBarAcquire)

         return false;

       // For other kinds of barriers, check by pretending we

       // are them, and seeing if we can be removed.

       else

         return post_store_load_barrier((const MemBarNode*)x);

     }

     // Delicate code to detect case of an upcoming fastlock block

     if( x->is_If() && x->req() > 1 &&

         !C->node_arena()->contains(x) ) { // Unmatched old-space only

       Node *iff = x;

       Node *bol = iff->in(1);

       // The iff might be some random subclass of If or bol might be Con-Top

       if (!bol->is_Bool())  return false;

       assert( bol->req() > 1, "" );

       return (bol->in(1)->Opcode() == Op_FastUnlock);

     }

     // probably not necessary to check for these

     if (x->is_Call() || x->is_SafePoint() || x->is_block_proj())

       return false;

   }

   return false;

 }

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

 //---------------------------State---------------------------------------------

 State::State(void) {

 #ifdef ASSERT

   _id = 0;

   _kids[0] = _kids[1] = (State*)(intptr_t) CONST64(0xcafebabecafebabe);

   _leaf = (Node*)(intptr_t) CONST64(0xbaadf00dbaadf00d);

   //memset(_cost, -1, sizeof(_cost));

   //memset(_rule, -1, sizeof(_rule));

 #endif

   memset(_valid, 0, sizeof(_valid));

 }

 #ifdef ASSERT

 State::~State() {

   _id = 99;

   _kids[0] = _kids[1] = (State*)(intptr_t) CONST64(0xcafebabecafebabe);

   _leaf = (Node*)(intptr_t) CONST64(0xbaadf00dbaadf00d);

   memset(_cost, -3, sizeof(_cost));

   memset(_rule, -3, sizeof(_rule));

 }

 #endif

 #ifndef PRODUCT

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

 void State::dump() {

   tty->print("\n");

   dump(0);

 }

 void State::dump(int depth) {

   for( int j = 0; j < depth; j++ )

     tty->print("   ");

   tty->print("--N: ");

   _leaf->dump();

   uint i;

   for( i = 0; i < _LAST_MACH_OPER; i++ )

     // Check for valid entry

     if( valid(i) ) {

       for( int j = 0; j < depth; j++ )

         tty->print("   ");

         assert(_cost[i] != max_juint, "cost must be a valid value");

         assert(_rule[i] < _last_Mach_Node, "rule[i] must be valid rule");

         tty->print_cr("%s  %d  %s",

                       ruleName[i], _cost[i], ruleName[_rule[i]] );

       }

   tty->print_cr("");

   for( i=0; i<2; i++ )

     if( _kids[i] )

       _kids[i]->dump(depth+1);

 }

 #endif