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 /*

  * Copyright (c) 1998, 2011, 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

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  */

 #include "precompiled.hpp"

 #include "memory/allocation.inline.hpp"

 #include "opto/block.hpp"

 #include "opto/c2compiler.hpp"

 #include "opto/callnode.hpp"

 #include "opto/cfgnode.hpp"

 #include "opto/machnode.hpp"

 #include "opto/runtime.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

 // Optimization - Graph Style

 //------------------------------implicit_null_check----------------------------

 // Detect implicit-null-check opportunities.  Basically, find NULL checks

 // with suitable memory ops nearby.  Use the memory op to do the NULL check.

 // I can generate a memory op if there is not one nearby.

 // The proj is the control projection for the not-null case.

 // The val is the pointer being checked for nullness or

 // decodeHeapOop_not_null node if it did not fold into address.

 void Block::implicit_null_check(PhaseCFG *cfg, Node *proj, Node *val, int allowed_reasons) {

   // Assume if null check need for 0 offset then always needed

   // Intel solaris doesn't support any null checks yet and no

   // mechanism exists (yet) to set the switches at an os_cpu level

   if( !ImplicitNullChecks || MacroAssembler::needs_explicit_null_check(0)) return;

   // Make sure the ptr-is-null path appears to be uncommon!

   float f = end()->as_MachIf()->_prob;

   if( proj->Opcode() == Op_IfTrue ) f = 1.0f - f;

   if( f > PROB_UNLIKELY_MAG(4) ) return;

   uint bidx = 0;                // Capture index of value into memop

   bool was_store;               // Memory op is a store op

   // Get the successor block for if the test ptr is non-null

   Block* not_null_block;  // this one goes with the proj

   Block* null_block;

   if (_nodes[_nodes.size()-1] == proj) {

     null_block     = _succs[0];

     not_null_block = _succs[1];

   } else {

     assert(_nodes[_nodes.size()-2] == proj, "proj is one or the other");

     not_null_block = _succs[0];

     null_block     = _succs[1];

   }

   while (null_block->is_Empty() == Block::empty_with_goto) {

     null_block     = null_block->_succs[0];

   }

   // Search the exception block for an uncommon trap.

   // (See Parse::do_if and Parse::do_ifnull for the reason

   // we need an uncommon trap.  Briefly, we need a way to

   // detect failure of this optimization, as in 6366351.)

   {

     bool found_trap = false;

     for (uint i1 = 0; i1 < null_block->_nodes.size(); i1++) {

       Node* nn = null_block->_nodes[i1];

       if (nn->is_MachCall() &&

           nn->as_MachCall()->entry_point() == SharedRuntime::uncommon_trap_blob()->entry_point()) {

         const Type* trtype = nn->in(TypeFunc::Parms)->bottom_type();

         if (trtype->isa_int() && trtype->is_int()->is_con()) {

           jint tr_con = trtype->is_int()->get_con();

           Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(tr_con);

           Deoptimization::DeoptAction action = Deoptimization::trap_request_action(tr_con);

           assert((int)reason < (int)BitsPerInt, "recode bit map");

           if (is_set_nth_bit(allowed_reasons, (int) reason)

               && action != Deoptimization::Action_none) {

             // This uncommon trap is sure to recompile, eventually.

             // When that happens, C->too_many_traps will prevent

             // this transformation from happening again.

             found_trap = true;

           }

         }

         break;

       }

     }

     if (!found_trap) {

       // We did not find an uncommon trap.

       return;

     }

   }

   // Check for decodeHeapOop_not_null node which did not fold into address

   bool is_decoden = ((intptr_t)val) & 1;

   val = (Node*)(((intptr_t)val) & ~1);

   assert(!is_decoden || (val->in(0) == NULL) && val->is_Mach() &&

          (val->as_Mach()->ideal_Opcode() == Op_DecodeN), "sanity");

   // Search the successor block for a load or store who's base value is also

   // the tested value.  There may be several.

   Node_List *out = new Node_List(Thread::current()->resource_area());

   MachNode *best = NULL;        // Best found so far

   for (DUIterator i = val->outs(); val->has_out(i); i++) {

     Node *m = val->out(i);

     if( !m->is_Mach() ) continue;

     MachNode *mach = m->as_Mach();

     was_store = false;

     int iop = mach->ideal_Opcode();

     switch( iop ) {

     case Op_LoadB:

     case Op_LoadUS:

     case Op_LoadD:

     case Op_LoadF:

     case Op_LoadI:

     case Op_LoadL:

     case Op_LoadP:

     case Op_LoadN:

     case Op_LoadS:

     case Op_LoadKlass:

     case Op_LoadNKlass:

     case Op_LoadRange:

     case Op_LoadD_unaligned:

     case Op_LoadL_unaligned:

       assert(mach->in(2) == val, "should be address");

       break;

     case Op_StoreB:

     case Op_StoreC:

     case Op_StoreCM:

     case Op_StoreD:

     case Op_StoreF:

     case Op_StoreI:

     case Op_StoreL:

     case Op_StoreP:

     case Op_StoreN:

       was_store = true;         // Memory op is a store op

       // Stores will have their address in slot 2 (memory in slot 1).

       // If the value being nul-checked is in another slot, it means we

       // are storing the checked value, which does NOT check the value!

       if( mach->in(2) != val ) continue;

       break;                    // Found a memory op?

     case Op_StrComp:

     case Op_StrEquals:

     case Op_StrIndexOf:

     case Op_AryEq:

       // Not a legit memory op for implicit null check regardless of

       // embedded loads

       continue;

     default:                    // Also check for embedded loads

       if( !mach->needs_anti_dependence_check() )

         continue;               // Not an memory op; skip it

       if( must_clone[iop] ) {

         // Do not move nodes which produce flags because

         // RA will try to clone it to place near branch and

         // it will cause recompilation, see clone_node().

         continue;

       }

       {

         // Check that value is used in memory address in

         // instructions with embedded load (CmpP val1,(val2+off)).

         Node* base;

         Node* index;

         const MachOper* oper = mach->memory_inputs(base, index);

         if (oper == NULL || oper == (MachOper*)-1) {

           continue;             // Not an memory op; skip it

         }

         if (val == base ||

             val == index && val->bottom_type()->isa_narrowoop()) {

           break;                // Found it

         } else {

           continue;             // Skip it

         }

       }

       break;

     }

     // check if the offset is not too high for implicit exception

     {

       intptr_t offset = 0;

       const TypePtr *adr_type = NULL;  // Do not need this return value here

       const Node* base = mach->get_base_and_disp(offset, adr_type);

       if (base == NULL || base == NodeSentinel) {

         // Narrow oop address doesn't have base, only index

         if( val->bottom_type()->isa_narrowoop() &&

             MacroAssembler::needs_explicit_null_check(offset) )

           continue;             // Give up if offset is beyond page size

         // cannot reason about it; is probably not implicit null exception

       } else {

         const TypePtr* tptr;

         if (UseCompressedOops && Universe::narrow_oop_shift() == 0) {

           // 32-bits narrow oop can be the base of address expressions

           tptr = base->bottom_type()->make_ptr();

         } else {

           // only regular oops are expected here

           tptr = base->bottom_type()->is_ptr();

         }

         // Give up if offset is not a compile-time constant

         if( offset == Type::OffsetBot || tptr->_offset == Type::OffsetBot )

           continue;

         offset += tptr->_offset; // correct if base is offseted

         if( MacroAssembler::needs_explicit_null_check(offset) )

           continue;             // Give up is reference is beyond 4K page size

       }

     }

     // Check ctrl input to see if the null-check dominates the memory op

     Block *cb = cfg->_bbs[mach->_idx];

     cb = cb->_idom;             // Always hoist at least 1 block

     if( !was_store ) {          // Stores can be hoisted only one block

       while( cb->_dom_depth > (_dom_depth + 1))

         cb = cb->_idom;         // Hoist loads as far as we want

       // The non-null-block should dominate the memory op, too. Live

       // range spilling will insert a spill in the non-null-block if it is

       // needs to spill the memory op for an implicit null check.

       if (cb->_dom_depth == (_dom_depth + 1)) {

         if (cb != not_null_block) continue;

         cb = cb->_idom;

       }

     }

     if( cb != this ) continue;

     // Found a memory user; see if it can be hoisted to check-block

     uint vidx = 0;              // Capture index of value into memop

     uint j;

     for( j = mach->req()-1; j > 0; j-- ) {

       if( mach->in(j) == val ) {

         vidx = j;

         // Ignore DecodeN val which could be hoisted to where needed.

         if( is_decoden ) continue;

       }

       // Block of memory-op input

       Block *inb = cfg->_bbs[mach->in(j)->_idx];

       Block *b = this;          // Start from nul check

       while( b != inb && b->_dom_depth > inb->_dom_depth )

         b = b->_idom;           // search upwards for input

       // See if input dominates null check

       if( b != inb )

         break;

     }

     if( j > 0 )

       continue;

     Block *mb = cfg->_bbs[mach->_idx];

     // Hoisting stores requires more checks for the anti-dependence case.

     // Give up hoisting if we have to move the store past any load.

     if( was_store ) {

       Block *b = mb;            // Start searching here for a local load

       // mach use (faulting) trying to hoist

       // n might be blocker to hoisting

       while( b != this ) {

         uint k;

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

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

           if( n->needs_anti_dependence_check() &&

               n->in(LoadNode::Memory) == mach->in(StoreNode::Memory) )

             break;              // Found anti-dependent load

         }

         if( k < b->_nodes.size() )

           break;                // Found anti-dependent load

         // Make sure control does not do a merge (would have to check allpaths)

         if( b->num_preds() != 2 ) break;

         b = cfg->_bbs[b->pred(1)->_idx]; // Move up to predecessor block

       }

       if( b != this ) continue;

     }

     // Make sure this memory op is not already being used for a NullCheck

     Node *e = mb->end();

     if( e->is_MachNullCheck() && e->in(1) == mach )

       continue;                 // Already being used as a NULL check

     // Found a candidate!  Pick one with least dom depth - the highest

     // in the dom tree should be closest to the null check.

     if( !best ||

         cfg->_bbs[mach->_idx]->_dom_depth < cfg->_bbs[best->_idx]->_dom_depth ) {

       best = mach;

       bidx = vidx;

     }

   }

   // No candidate!

   if( !best ) return;

   // ---- Found an implicit null check

   extern int implicit_null_checks;

   implicit_null_checks++;

   if( is_decoden ) {

     // Check if we need to hoist decodeHeapOop_not_null first.

     Block *valb = cfg->_bbs[val->_idx];

     if( this != valb && this->_dom_depth < valb->_dom_depth ) {

       // Hoist it up to the end of the test block.

       valb->find_remove(val);

       this->add_inst(val);

       cfg->_bbs.map(val->_idx,this);

       // DecodeN on x86 may kill flags. Check for flag-killing projections

       // that also need to be hoisted.

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

         Node* n = val->fast_out(j);

         if( n->Opcode() == Op_MachProj ) {

           cfg->_bbs[n->_idx]->find_remove(n);

           this->add_inst(n);

           cfg->_bbs.map(n->_idx,this);

         }

       }

     }

   }

   // Hoist the memory candidate up to the end of the test block.

   Block *old_block = cfg->_bbs[best->_idx];

   old_block->find_remove(best);

   add_inst(best);

   cfg->_bbs.map(best->_idx,this);

   // Move the control dependence

   if (best->in(0) && best->in(0) == old_block->_nodes[0])

     best->set_req(0, _nodes[0]);

   // Check for flag-killing projections that also need to be hoisted

   // Should be DU safe because no edge updates.

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

     Node* n = best->fast_out(j);

     if( n->Opcode() == Op_MachProj ) {

       cfg->_bbs[n->_idx]->find_remove(n);

       add_inst(n);

       cfg->_bbs.map(n->_idx,this);

     }

   }

   Compile *C = cfg->C;

   // proj==Op_True --> ne test; proj==Op_False --> eq test.

   // One of two graph shapes got matched:

   //   (IfTrue  (If (Bool NE (CmpP ptr NULL))))

   //   (IfFalse (If (Bool EQ (CmpP ptr NULL))))

   // NULL checks are always branch-if-eq.  If we see a IfTrue projection

   // then we are replacing a 'ne' test with a 'eq' NULL check test.

   // We need to flip the projections to keep the same semantics.

   if( proj->Opcode() == Op_IfTrue ) {

     // Swap order of projections in basic block to swap branch targets

     Node *tmp1 = _nodes[end_idx()+1];

     Node *tmp2 = _nodes[end_idx()+2];

     _nodes.map(end_idx()+1, tmp2);

     _nodes.map(end_idx()+2, tmp1);

     Node *tmp = new (C, 1) Node(C->top()); // Use not NULL input

     tmp1->replace_by(tmp);

     tmp2->replace_by(tmp1);

     tmp->replace_by(tmp2);

     tmp->destruct();

   }

   // Remove the existing null check; use a new implicit null check instead.

   // Since schedule-local needs precise def-use info, we need to correct

   // it as well.

   Node *old_tst = proj->in(0);

   MachNode *nul_chk = new (C) MachNullCheckNode(old_tst->in(0),best,bidx);

   _nodes.map(end_idx(),nul_chk);

   cfg->_bbs.map(nul_chk->_idx,this);

   // Redirect users of old_test to nul_chk

   for (DUIterator_Last i2min, i2 = old_tst->last_outs(i2min); i2 >= i2min; --i2)

     old_tst->last_out(i2)->set_req(0, nul_chk);

   // Clean-up any dead code

   for (uint i3 = 0; i3 < old_tst->req(); i3++)

     old_tst->set_req(i3, NULL);

   cfg->latency_from_uses(nul_chk);

   cfg->latency_from_uses(best);

 }

 //------------------------------select-----------------------------------------

 // Select a nice fellow from the worklist to schedule next. If there is only

 // one choice, then use it. Projections take top priority for correctness

 // reasons - if I see a projection, then it is next.  There are a number of

 // other special cases, for instructions that consume condition codes, et al.

 // These are chosen immediately. Some instructions are required to immediately

 // precede the last instruction in the block, and these are taken last. Of the

 // remaining cases (most), choose the instruction with the greatest latency

 // (that is, the most number of pseudo-cycles required to the end of the

 // routine). If there is a tie, choose the instruction with the most inputs.

 Node *Block::select(PhaseCFG *cfg, Node_List &worklist, int *ready_cnt, VectorSet &next_call, uint sched_slot) {

   // If only a single entry on the stack, use it

   uint cnt = worklist.size();

   if (cnt == 1) {

     Node *n = worklist[0];

     worklist.map(0,worklist.pop());

     return n;

   }

   uint choice  = 0; // Bigger is most important

   uint latency = 0; // Bigger is scheduled first

   uint score   = 0; // Bigger is better

   int idx = -1;     // Index in worklist

   for( uint i=0; i<cnt; i++ ) { // Inspect entire worklist

     // Order in worklist is used to break ties.

     // See caller for how this is used to delay scheduling

     // of induction variable increments to after the other

     // uses of the phi are scheduled.

     Node *n = worklist[i];      // Get Node on worklist

     int iop = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : 0;

     if( n->is_Proj() ||         // Projections always win

         n->Opcode()== Op_Con || // So does constant 'Top'

         iop == Op_CreateEx ||   // Create-exception must start block

         iop == Op_CheckCastPP

         ) {

       worklist.map(i,worklist.pop());

       return n;

     }

     // Final call in a block must be adjacent to 'catch'

     Node *e = end();

     if( e->is_Catch() && e->in(0)->in(0) == n )

       continue;

     // Memory op for an implicit null check has to be at the end of the block

     if( e->is_MachNullCheck() && e->in(1) == n )

       continue;

     uint n_choice  = 2;

     // See if this instruction is consumed by a branch. If so, then (as the

     // branch is the last instruction in the basic block) force it to the

     // end of the basic block

     if ( must_clone[iop] ) {

       // See if any use is a branch

       bool found_machif = false;

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

         Node* use = n->fast_out(j);

         // The use is a conditional branch, make them adjacent

         if (use->is_MachIf() && cfg->_bbs[use->_idx]==this ) {

           found_machif = true;

           break;

         }

         // More than this instruction pending for successor to be ready,

         // don't choose this if other opportunities are ready

         if (ready_cnt[use->_idx] > 1)

           n_choice = 1;

       }

       // loop terminated, prefer not to use this instruction

       if (found_machif)

         continue;

     }

     // See if this has a predecessor that is "must_clone", i.e. sets the

     // condition code. If so, choose this first

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

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

       if (inn) {

         if (inn->is_Mach() && must_clone[inn->as_Mach()->ideal_Opcode()] ) {

           n_choice = 3;

           break;

         }

       }

     }

     // MachTemps should be scheduled last so they are near their uses

     if (n->is_MachTemp()) {

       n_choice = 1;

     }

     uint n_latency = cfg->_node_latency->at_grow(n->_idx);

     uint n_score   = n->req();   // Many inputs get high score to break ties

     // Keep best latency found

     if( choice < n_choice ||

         ( choice == n_choice &&

           ( latency < n_latency ||

             ( latency == n_latency &&

               ( score < n_score ))))) {

       choice  = n_choice;

       latency = n_latency;

       score   = n_score;

       idx     = i;               // Also keep index in worklist

     }

   } // End of for all ready nodes in worklist

   assert(idx >= 0, "index should be set");

   Node *n = worklist[(uint)idx];      // Get the winner

   worklist.map((uint)idx, worklist.pop());     // Compress worklist

   return n;

 }

 //------------------------------set_next_call----------------------------------

 void Block::set_next_call( Node *n, VectorSet &next_call, Block_Array &bbs ) {

   if( next_call.test_set(n->_idx) ) return;

   for( uint i=0; i<n->len(); i++ ) {

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

     if( !m ) continue;  // must see all nodes in block that precede call

     if( bbs[m->_idx] == this )

       set_next_call( m, next_call, bbs );

   }

 }

 //------------------------------needed_for_next_call---------------------------

 // Set the flag 'next_call' for each Node that is needed for the next call to

 // be scheduled.  This flag lets me bias scheduling so Nodes needed for the

 // next subroutine call get priority - basically it moves things NOT needed

 // for the next call till after the call.  This prevents me from trying to

 // carry lots of stuff live across a call.

 void Block::needed_for_next_call(Node *this_call, VectorSet &next_call, Block_Array &bbs) {

   // Find the next control-defining Node in this block

   Node* call = NULL;

   for (DUIterator_Fast imax, i = this_call->fast_outs(imax); i < imax; i++) {

     Node* m = this_call->fast_out(i);

     if( bbs[m->_idx] == this && // Local-block user

         m != this_call &&       // Not self-start node

         m->is_Call() )

       call = m;

       break;

   }

   if (call == NULL)  return;    // No next call (e.g., block end is near)

   // Set next-call for all inputs to this call

   set_next_call(call, next_call, bbs);

 }

 //------------------------------sched_call-------------------------------------

 uint Block::sched_call( Matcher &matcher, Block_Array &bbs, uint node_cnt, Node_List &worklist, int *ready_cnt, MachCallNode *mcall, VectorSet &next_call ) {

   RegMask regs;

   // Schedule all the users of the call right now.  All the users are

   // projection Nodes, so they must be scheduled next to the call.

   // Collect all the defined registers.

   for (DUIterator_Fast imax, i = mcall->fast_outs(imax); i < imax; i++) {

     Node* n = mcall->fast_out(i);

     assert( n->Opcode()==Op_MachProj, "" );

     --ready_cnt[n->_idx];

     assert( !ready_cnt[n->_idx], "" );

     // Schedule next to call

     _nodes.map(node_cnt++, n);

     // Collect defined registers

     regs.OR(n->out_RegMask());

     // Check for scheduling the next control-definer

     if( n->bottom_type() == Type::CONTROL )

       // Warm up next pile of heuristic bits

       needed_for_next_call(n, next_call, bbs);

     // Children of projections are now all ready

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

       Node* m = n->fast_out(j); // Get user

       if( bbs[m->_idx] != this ) continue;

       if( m->is_Phi() ) continue;

       if( !--ready_cnt[m->_idx] )

         worklist.push(m);

     }

   }

   // Act as if the call defines the Frame Pointer.

   // Certainly the FP is alive and well after the call.

   regs.Insert(matcher.c_frame_pointer());

   // Set all registers killed and not already defined by the call.

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

   int op = mcall->ideal_Opcode();

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

   bbs.map(proj->_idx,this);

   _nodes.insert(node_cnt++, proj);

   // Select the right register save policy.

   const char * save_policy;

   switch (op) {

     case Op_CallRuntime:

     case Op_CallLeaf:

     case Op_CallLeafNoFP:

       // Calling C code so use C calling convention

       save_policy = matcher._c_reg_save_policy;

       break;

     case Op_CallStaticJava:

     case Op_CallDynamicJava:

       // Calling Java code so use Java calling convention

       save_policy = matcher._register_save_policy;

       break;

     default:

       ShouldNotReachHere();

   }

   // When using CallRuntime mark SOE registers as killed by the call

   // so values that could show up in the RegisterMap aren't live in a

   // callee saved register since the register wouldn't know where to

   // find them.  CallLeaf and CallLeafNoFP are ok because they can't

   // have debug info on them.  Strictly speaking this only needs to be

   // done for oops since idealreg2debugmask takes care of debug info

   // references but there no way to handle oops differently than other

   // pointers as far as the kill mask goes.

   bool exclude_soe = op == Op_CallRuntime;

   // If the call is a MethodHandle invoke, we need to exclude the

   // register which is used to save the SP value over MH invokes from

   // the mask.  Otherwise this register could be used for

   // deoptimization information.

   if (op == Op_CallStaticJava) {

     MachCallStaticJavaNode* mcallstaticjava = (MachCallStaticJavaNode*) mcall;

     if (mcallstaticjava->_method_handle_invoke)

       proj->_rout.OR(Matcher::method_handle_invoke_SP_save_mask());

   }

   // Fill in the kill mask for the call

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

     if( !regs.Member(r) ) {     // Not already defined by the call

       // Save-on-call register?

       if ((save_policy[r] == 'C') ||

           (save_policy[r] == 'A') ||

           ((save_policy[r] == 'E') && exclude_soe)) {

         proj->_rout.Insert(r);

       }

     }

   }

   return node_cnt;

 }

 //------------------------------schedule_local---------------------------------

 // Topological sort within a block.  Someday become a real scheduler.

 bool Block::schedule_local(PhaseCFG *cfg, Matcher &matcher, int *ready_cnt, VectorSet &next_call) {

   // Already "sorted" are the block start Node (as the first entry), and

   // the block-ending Node and any trailing control projections.  We leave

   // these alone.  PhiNodes and ParmNodes are made to follow the block start

   // Node.  Everything else gets topo-sorted.

 #ifndef PRODUCT

     if (cfg->trace_opto_pipelining()) {

       tty->print_cr("# --- schedule_local B%d, before: ---", _pre_order);

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

         tty->print("# ");

         _nodes[i]->fast_dump();

       }

       tty->print_cr("#");

     }

 #endif

   // RootNode is already sorted

   if( _nodes.size() == 1 ) return true;

   // Move PhiNodes and ParmNodes from 1 to cnt up to the start

   uint node_cnt = end_idx();

   uint phi_cnt = 1;

   uint i;

   for( i = 1; i<node_cnt; i++ ) { // Scan for Phi

     Node *n = _nodes[i];

     if( n->is_Phi() ||          // Found a PhiNode or ParmNode

         (n->is_Proj()  && n->in(0) == head()) ) {

       // Move guy at 'phi_cnt' to the end; makes a hole at phi_cnt

       _nodes.map(i,_nodes[phi_cnt]);

       _nodes.map(phi_cnt++,n);  // swap Phi/Parm up front

     } else {                    // All others

       // Count block-local inputs to 'n'

       uint cnt = n->len();      // Input count

       uint local = 0;

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

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

         if( m && cfg->_bbs[m->_idx] == this && !m->is_top() )

           local++;              // One more block-local input

       }

       ready_cnt[n->_idx] = local; // Count em up

 #ifdef ASSERT

       if( UseConcMarkSweepGC || UseG1GC ) {

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

           // Check the precedence edges

           for (uint prec = n->req(); prec < n->len(); prec++) {

             Node* oop_store = n->in(prec);

             if (oop_store != NULL) {

               assert(cfg->_bbs[oop_store->_idx]->_dom_depth <= this->_dom_depth, "oop_store must dominate card-mark");

             }

           }

         }

       }

 #endif

       // A few node types require changing a required edge to a precedence edge

       // before allocation.

       if( n->is_Mach() && n->req() > TypeFunc::Parms &&

           (n->as_Mach()->ideal_Opcode() == Op_MemBarAcquire ||

            n->as_Mach()->ideal_Opcode() == Op_MemBarVolatile) ) {

         // MemBarAcquire could be created without Precedent edge.

         // del_req() replaces the specified edge with the last input edge

         // and then removes the last edge. If the specified edge > number of

         // edges the last edge will be moved outside of the input edges array

         // and the edge will be lost. This is why this code should be

         // executed only when Precedent (== TypeFunc::Parms) edge is present.

         Node *x = n->in(TypeFunc::Parms);

         n->del_req(TypeFunc::Parms);

         n->add_prec(x);

       }

     }

   }

   for(uint i2=i; i2<_nodes.size(); i2++ ) // Trailing guys get zapped count

     ready_cnt[_nodes[i2]->_idx] = 0;

   // All the prescheduled guys do not hold back internal nodes

   uint i3;

   for(i3 = 0; i3<phi_cnt; i3++ ) {  // For all pre-scheduled

     Node *n = _nodes[i3];       // Get pre-scheduled

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

       Node* m = n->fast_out(j);

       if( cfg->_bbs[m->_idx] ==this ) // Local-block user

         ready_cnt[m->_idx]--;   // Fix ready count

     }

   }

   Node_List delay;

   // Make a worklist

   Node_List worklist;

   for(uint i4=i3; i4<node_cnt; i4++ ) {    // Put ready guys on worklist

     Node *m = _nodes[i4];

     if( !ready_cnt[m->_idx] ) {   // Zero ready count?

       if (m->is_iteratively_computed()) {

         // Push induction variable increments last to allow other uses

         // of the phi to be scheduled first. The select() method breaks

         // ties in scheduling by worklist order.

         delay.push(m);

       } else if (m->is_Mach() && m->as_Mach()->ideal_Opcode() == Op_CreateEx) {

         // Force the CreateEx to the top of the list so it's processed

         // first and ends up at the start of the block.

         worklist.insert(0, m);

       } else {

         worklist.push(m);         // Then on to worklist!

       }

     }

   }

   while (delay.size()) {

     Node* d = delay.pop();

     worklist.push(d);

   }

   // Warm up the 'next_call' heuristic bits

   needed_for_next_call(_nodes[0], next_call, cfg->_bbs);

 #ifndef PRODUCT

     if (cfg->trace_opto_pipelining()) {

       for (uint j=0; j<_nodes.size(); j++) {

         Node     *n = _nodes[j];

         int     idx = n->_idx;

         tty->print("#   ready cnt:%3d  ", ready_cnt[idx]);

         tty->print("latency:%3d  ", cfg->_node_latency->at_grow(idx));

         tty->print("%4d: %s\n", idx, n->Name());

       }

     }

 #endif

   // Pull from worklist and schedule

   while( worklist.size() ) {    // Worklist is not ready

 #ifndef PRODUCT

     if (cfg->trace_opto_pipelining()) {

       tty->print("#   ready list:");

       for( uint i=0; i<worklist.size(); i++ ) { // Inspect entire worklist

         Node *n = worklist[i];      // Get Node on worklist

         tty->print(" %d", n->_idx);

       }

       tty->cr();

     }

 #endif

     // Select and pop a ready guy from worklist

     Node* n = select(cfg, worklist, ready_cnt, next_call, phi_cnt);

     _nodes.map(phi_cnt++,n);    // Schedule him next

 #ifndef PRODUCT

     if (cfg->trace_opto_pipelining()) {

       tty->print("#    select %d: %s", n->_idx, n->Name());

       tty->print(", latency:%d", cfg->_node_latency->at_grow(n->_idx));

       n->dump();

       if (Verbose) {

         tty->print("#   ready list:");

         for( uint i=0; i<worklist.size(); i++ ) { // Inspect entire worklist

           Node *n = worklist[i];      // Get Node on worklist

           tty->print(" %d", n->_idx);

         }

         tty->cr();

       }

     }

 #endif

     if( n->is_MachCall() ) {

       MachCallNode *mcall = n->as_MachCall();

       phi_cnt = sched_call(matcher, cfg->_bbs, phi_cnt, worklist, ready_cnt, mcall, next_call);

       continue;

     }

     // Children are now all ready

     for (DUIterator_Fast i5max, i5 = n->fast_outs(i5max); i5 < i5max; i5++) {

       Node* m = n->fast_out(i5); // Get user

       if( cfg->_bbs[m->_idx] != this ) continue;

       if( m->is_Phi() ) continue;

       if( !--ready_cnt[m->_idx] )

         worklist.push(m);

     }

   }

   if( phi_cnt != end_idx() ) {

     // did not schedule all.  Retry, Bailout, or Die

     Compile* C = matcher.C;

     if (C->subsume_loads() == true && !C->failing()) {

       // Retry with subsume_loads == false

       // If this is the first failure, the sentinel string will "stick"

       // to the Compile object, and the C2Compiler will see it and retry.

       C->record_failure(C2Compiler::retry_no_subsuming_loads());

     }

     // assert( phi_cnt == end_idx(), "did not schedule all" );

     return false;

   }

 #ifndef PRODUCT

   if (cfg->trace_opto_pipelining()) {

     tty->print_cr("#");

     tty->print_cr("# after schedule_local");

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

       tty->print("# ");

       _nodes[i]->fast_dump();

     }

     tty->cr();

   }

 #endif

   return true;

 }

 //--------------------------catch_cleanup_fix_all_inputs-----------------------

 static void catch_cleanup_fix_all_inputs(Node *use, Node *old_def, Node *new_def) {

   for (uint l = 0; l < use->len(); l++) {

     if (use->in(l) == old_def) {

       if (l < use->req()) {

         use->set_req(l, new_def);

       } else {

         use->rm_prec(l);

         use->add_prec(new_def);

         l--;

       }

     }

   }

 }

 //------------------------------catch_cleanup_find_cloned_def------------------

 static Node *catch_cleanup_find_cloned_def(Block *use_blk, Node *def, Block *def_blk, Block_Array &bbs, int n_clone_idx) {

   assert( use_blk != def_blk, "Inter-block cleanup only");

   // The use is some block below the Catch.  Find and return the clone of the def

   // that dominates the use. If there is no clone in a dominating block, then

   // create a phi for the def in a dominating block.

   // Find which successor block dominates this use.  The successor

   // blocks must all be single-entry (from the Catch only; I will have

   // split blocks to make this so), hence they all dominate.

   while( use_blk->_dom_depth > def_blk->_dom_depth+1 )

     use_blk = use_blk->_idom;

   // Find the successor

   Node *fixup = NULL;

   uint j;

   for( j = 0; j < def_blk->_num_succs; j++ )

     if( use_blk == def_blk->_succs[j] )

       break;

   if( j == def_blk->_num_succs ) {

     // Block at same level in dom-tree is not a successor.  It needs a

     // PhiNode, the PhiNode uses from the def and IT's uses need fixup.

     Node_Array inputs = new Node_List(Thread::current()->resource_area());

     for(uint k = 1; k < use_blk->num_preds(); k++) {

       inputs.map(k, catch_cleanup_find_cloned_def(bbs[use_blk->pred(k)->_idx], def, def_blk, bbs, n_clone_idx));

     }

     // Check to see if the use_blk already has an identical phi inserted.

     // If it exists, it will be at the first position since all uses of a

     // def are processed together.

     Node *phi = use_blk->_nodes[1];

     if( phi->is_Phi() ) {

       fixup = phi;

       for (uint k = 1; k < use_blk->num_preds(); k++) {

         if (phi->in(k) != inputs[k]) {

           // Not a match

           fixup = NULL;

           break;

         }

       }

     }

     // If an existing PhiNode was not found, make a new one.

     if (fixup == NULL) {

       Node *new_phi = PhiNode::make(use_blk->head(), def);

       use_blk->_nodes.insert(1, new_phi);

       bbs.map(new_phi->_idx, use_blk);

       for (uint k = 1; k < use_blk->num_preds(); k++) {

         new_phi->set_req(k, inputs[k]);

       }

       fixup = new_phi;

     }

   } else {

     // Found the use just below the Catch.  Make it use the clone.

     fixup = use_blk->_nodes[n_clone_idx];

   }

   return fixup;

 }

 //--------------------------catch_cleanup_intra_block--------------------------

 // Fix all input edges in use that reference "def".  The use is in the same

 // block as the def and both have been cloned in each successor block.

 static void catch_cleanup_intra_block(Node *use, Node *def, Block *blk, int beg, int n_clone_idx) {

   // Both the use and def have been cloned. For each successor block,

   // get the clone of the use, and make its input the clone of the def

   // found in that block.

   uint use_idx = blk->find_node(use);

   uint offset_idx = use_idx - beg;

   for( uint k = 0; k < blk->_num_succs; k++ ) {

     // Get clone in each successor block

     Block *sb = blk->_succs[k];

     Node *clone = sb->_nodes[offset_idx+1];

     assert( clone->Opcode() == use->Opcode(), "" );

     // Make use-clone reference the def-clone

     catch_cleanup_fix_all_inputs(clone, def, sb->_nodes[n_clone_idx]);

   }

 }

 //------------------------------catch_cleanup_inter_block---------------------

 // Fix all input edges in use that reference "def".  The use is in a different

 // block than the def.

 static void catch_cleanup_inter_block(Node *use, Block *use_blk, Node *def, Block *def_blk, Block_Array &bbs, int n_clone_idx) {

   if( !use_blk ) return;        // Can happen if the use is a precedence edge

   Node *new_def = catch_cleanup_find_cloned_def(use_blk, def, def_blk, bbs, n_clone_idx);

   catch_cleanup_fix_all_inputs(use, def, new_def);

 }

 //------------------------------call_catch_cleanup-----------------------------

 // If we inserted any instructions between a Call and his CatchNode,

 // clone the instructions on all paths below the Catch.

 void Block::call_catch_cleanup(Block_Array &bbs) {

   // End of region to clone

   uint end = end_idx();

   if( !_nodes[end]->is_Catch() ) return;

   // Start of region to clone

   uint beg = end;

   while( _nodes[beg-1]->Opcode() != Op_MachProj ||

         !_nodes[beg-1]->in(0)->is_Call() ) {

     beg--;

     assert(beg > 0,"Catch cleanup walking beyond block boundary");

   }

   // Range of inserted instructions is [beg, end)

   if( beg == end ) return;

   // Clone along all Catch output paths.  Clone area between the 'beg' and

   // 'end' indices.

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

     Block *sb = _succs[i];

     // Clone the entire area; ignoring the edge fixup for now.

     for( uint j = end; j > beg; j-- ) {

       // It is safe here to clone a node with anti_dependence

       // since clones dominate on each path.

       Node *clone = _nodes[j-1]->clone();

       sb->_nodes.insert( 1, clone );

       bbs.map(clone->_idx,sb);

     }

   }

   // Fixup edges.  Check the def-use info per cloned Node

   for(uint i2 = beg; i2 < end; i2++ ) {

     uint n_clone_idx = i2-beg+1; // Index of clone of n in each successor block

     Node *n = _nodes[i2];        // Node that got cloned

     // Need DU safe iterator because of edge manipulation in calls.

     Unique_Node_List *out = new Unique_Node_List(Thread::current()->resource_area());

     for (DUIterator_Fast j1max, j1 = n->fast_outs(j1max); j1 < j1max; j1++) {

       out->push(n->fast_out(j1));

     }

     uint max = out->size();

     for (uint j = 0; j < max; j++) {// For all users

       Node *use = out->pop();

       Block *buse = bbs[use->_idx];

       if( use->is_Phi() ) {

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

           if( use->in(k) == n ) {

             Node *fixup = catch_cleanup_find_cloned_def(bbs[buse->pred(k)->_idx], n, this, bbs, n_clone_idx);

             use->set_req(k, fixup);

           }

       } else {

         if (this == buse) {

           catch_cleanup_intra_block(use, n, this, beg, n_clone_idx);

         } else {

           catch_cleanup_inter_block(use, buse, n, this, bbs, n_clone_idx);

         }

       }

     } // End for all users

   } // End of for all Nodes in cloned area

   // Remove the now-dead cloned ops

   for(uint i3 = beg; i3 < end; i3++ ) {

     _nodes[beg]->disconnect_inputs(NULL);

     _nodes.remove(beg);

   }

   // If the successor blocks have a CreateEx node, move it back to the top

   for(uint i4 = 0; i4 < _num_succs; i4++ ) {

     Block *sb = _succs[i4];

     uint new_cnt = end - beg;

     // Remove any newly created, but dead, nodes.

     for( uint j = new_cnt; j > 0; j-- ) {

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

       if (n->outcnt() == 0 &&

           (!n->is_Proj() || n->as_Proj()->in(0)->outcnt() == 1) ){

         n->disconnect_inputs(NULL);

         sb->_nodes.remove(j);

         new_cnt--;

       }

     }

     // If any newly created nodes remain, move the CreateEx node to the top

     if (new_cnt > 0) {

       Node *cex = sb->_nodes[1+new_cnt];

       if( cex->is_Mach() && cex->as_Mach()->ideal_Opcode() == Op_CreateEx ) {

         sb->_nodes.remove(1+new_cnt);

         sb->_nodes.insert(1,cex);

       }

     }

   }

 }