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 /*

  * Copyright (c) 1999, 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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  */

 #ifndef SHARE_VM_C1_C1_VALUEMAP_HPP

 #define SHARE_VM_C1_C1_VALUEMAP_HPP

 #include "c1/c1_Instruction.hpp"

 #include "c1/c1_ValueSet.hpp"

 #include "memory/allocation.hpp"

 class ValueMapEntry: public CompilationResourceObj {

  private:

   intx           _hash;

   Value          _value;

   int            _nesting;

   ValueMapEntry* _next;

  public:

   ValueMapEntry(intx hash, Value value, int nesting, ValueMapEntry* next)

     : _hash(hash)

     , _value(value)

     , _nesting(nesting)

     , _next(next)

   {

   }

   intx           hash()      { return _hash; }

   Value          value()     { return _value; }

   int            nesting()   { return _nesting; }

   ValueMapEntry* next()      { return _next; }

   void set_next(ValueMapEntry* next) { _next = next; }

 };

 define_array(ValueMapEntryArray, ValueMapEntry*)

 define_stack(ValueMapEntryList, ValueMapEntryArray)

 // ValueMap implements nested hash tables for value numbering.  It

 // maintains a set _killed_values which represents the instructions

 // which have been killed so far and an array of linked lists of

 // ValueMapEntries names _entries.  Each ValueMapEntry has a nesting

 // which indicates what ValueMap nesting it belongs to.  Higher

 // nesting values are always before lower values in the linked list.

 // This allows cloning of parent ValueMaps by simply copying the heads

 // of the list.  _entry_count represents the number of reachable

 // entries in the ValueMap.  A ValueMap is only allowed to mutate

 // ValueMapEntries with the same nesting level.  Adding or removing

 // entries at the current nesting level requires updating

 // _entry_count.  Elements in the parent's list that get killed can be

 // skipped if they are at the head of the list by simply moving to the

 // next element in the list and decrementing _entry_count.

 class ValueMap: public CompilationResourceObj {

  private:

   int           _nesting;

   ValueMapEntryArray _entries;

   ValueSet      _killed_values;

   int           _entry_count;

   int           nesting()                        { return _nesting; }

   bool          is_local_value_numbering()       { return _nesting == 0; }

   bool          is_global_value_numbering()      { return _nesting > 0; }

   int           entry_count()                    { return _entry_count; }

   int           size()                           { return _entries.length(); }

   ValueMapEntry* entry_at(int i)                 { return _entries.at(i); }

   // calculates the index of a hash value in a hash table of size n

   int           entry_index(intx hash, int n)    { return (unsigned int)hash % n; }

   // if entry_count > size_threshold, the size of the hash table is increased

   int           size_threshold()                 { return size(); }

   // management of the killed-bitset for global value numbering

   void          kill_value(Value v)              { if (is_global_value_numbering()) _killed_values.put(v); }

   bool          is_killed(Value v)               { if (is_global_value_numbering()) return _killed_values.contains(v); else return false; }

   // helper functions

   void          increase_table_size();

 #ifndef PRODUCT

   static int _number_of_finds;

   static int _number_of_hits;

   static int _number_of_kills;

 #endif // PRODUCT

  public:

   // creation

   ValueMap();                // empty value map

   ValueMap(ValueMap* old);   // value map with increased nesting

   // manipulation

   Value find_insert(Value x);

   void kill_memory();

   void kill_field(ciField* field, bool all_offsets);

   void kill_array(ValueType* type);

   void kill_exception();

   void kill_map(ValueMap* map);

   void kill_all();

 #ifndef PRODUCT

   // debugging/printing

   void print();

   static void reset_statistics();

   static void print_statistics();

 #endif

 };

 define_array(ValueMapArray, ValueMap*)

 class ValueNumberingVisitor: public InstructionVisitor {

  protected:

   // called by visitor functions for instructions that kill values

   virtual void kill_memory() = 0;

   virtual void kill_field(ciField* field, bool all_offsets) = 0;

   virtual void kill_array(ValueType* type) = 0;

   // visitor functions

   void do_StoreField     (StoreField*      x) {

     if (x->is_init_point() ||  // putstatic is an initialization point so treat it as a wide kill

         // This is actually too strict and the JMM doesn't require

         // this in all cases (e.g. load a; volatile store b; load a)

         // but possible future optimizations might require this.

         x->field()->is_volatile()) {

       kill_memory();

     } else {

       kill_field(x->field(), x->needs_patching());

     }

   }

   void do_StoreIndexed   (StoreIndexed*    x) { kill_array(x->type()); }

   void do_MonitorEnter   (MonitorEnter*    x) { kill_memory(); }

   void do_MonitorExit    (MonitorExit*     x) { kill_memory(); }

   void do_Invoke         (Invoke*          x) { kill_memory(); }

   void do_UnsafePutRaw   (UnsafePutRaw*    x) { kill_memory(); }

   void do_UnsafePutObject(UnsafePutObject* x) { kill_memory(); }

   void do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) { kill_memory(); }

   void do_Intrinsic      (Intrinsic*       x) { if (!x->preserves_state()) kill_memory(); }

   void do_Phi            (Phi*             x) { /* nothing to do */ }

   void do_Local          (Local*           x) { /* nothing to do */ }

   void do_Constant       (Constant*        x) { /* nothing to do */ }

   void do_LoadField      (LoadField*       x) {

     if (x->is_init_point() ||         // getstatic is an initialization point so treat it as a wide kill

         x->field()->is_volatile()) {  // the JMM requires this

       kill_memory();

     }

   }

   void do_ArrayLength    (ArrayLength*     x) { /* nothing to do */ }

   void do_LoadIndexed    (LoadIndexed*     x) { /* nothing to do */ }

   void do_NegateOp       (NegateOp*        x) { /* nothing to do */ }

   void do_ArithmeticOp   (ArithmeticOp*    x) { /* nothing to do */ }

   void do_ShiftOp        (ShiftOp*         x) { /* nothing to do */ }

   void do_LogicOp        (LogicOp*         x) { /* nothing to do */ }

   void do_CompareOp      (CompareOp*       x) { /* nothing to do */ }

   void do_IfOp           (IfOp*            x) { /* nothing to do */ }

   void do_Convert        (Convert*         x) { /* nothing to do */ }

   void do_NullCheck      (NullCheck*       x) { /* nothing to do */ }

   void do_TypeCast       (TypeCast*        x) { /* nothing to do */ }

   void do_NewInstance    (NewInstance*     x) { /* nothing to do */ }

   void do_NewTypeArray   (NewTypeArray*    x) { /* nothing to do */ }

   void do_NewObjectArray (NewObjectArray*  x) { /* nothing to do */ }

   void do_NewMultiArray  (NewMultiArray*   x) { /* nothing to do */ }

   void do_CheckCast      (CheckCast*       x) { /* nothing to do */ }

   void do_InstanceOf     (InstanceOf*      x) { /* nothing to do */ }

   void do_BlockBegin     (BlockBegin*      x) { /* nothing to do */ }

   void do_Goto           (Goto*            x) { /* nothing to do */ }

   void do_If             (If*              x) { /* nothing to do */ }

   void do_IfInstanceOf   (IfInstanceOf*    x) { /* nothing to do */ }

   void do_TableSwitch    (TableSwitch*     x) { /* nothing to do */ }

   void do_LookupSwitch   (LookupSwitch*    x) { /* nothing to do */ }

   void do_Return         (Return*          x) { /* nothing to do */ }

   void do_Throw          (Throw*           x) { /* nothing to do */ }

   void do_Base           (Base*            x) { /* nothing to do */ }

   void do_OsrEntry       (OsrEntry*        x) { /* nothing to do */ }

   void do_ExceptionObject(ExceptionObject* x) { /* nothing to do */ }

   void do_RoundFP        (RoundFP*         x) { /* nothing to do */ }

   void do_UnsafeGetRaw   (UnsafeGetRaw*    x) { /* nothing to do */ }

   void do_UnsafeGetObject(UnsafeGetObject* x) { /* nothing to do */ }

   void do_UnsafePrefetchRead (UnsafePrefetchRead*  x) { /* nothing to do */ }

   void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) { /* nothing to do */ }

   void do_ProfileCall    (ProfileCall*     x) { /* nothing to do */ }

   void do_ProfileInvoke  (ProfileInvoke*   x) { /* nothing to do */ };

   void do_RuntimeCall    (RuntimeCall*     x) { /* nothing to do */ };

   void do_MemBar         (MemBar*          x) { /* nothing to do */ };

   void do_RangeCheckPredicate(RangeCheckPredicate* x) { /* nothing to do */ };

   void do_Assert         (Assert*          x) { /* nothing to do */ };

 };

 class ValueNumberingEffects: public ValueNumberingVisitor {

  private:

   ValueMap*     _map;

  public:

   // implementation for abstract methods of ValueNumberingVisitor

   void          kill_memory()                                 { _map->kill_memory(); }

   void          kill_field(ciField* field, bool all_offsets)  { _map->kill_field(field, all_offsets); }

   void          kill_array(ValueType* type)                   { _map->kill_array(type); }

   ValueNumberingEffects(ValueMap* map): _map(map) {}

 };

 class GlobalValueNumbering: public ValueNumberingVisitor {

  private:

   Compilation*  _compilation;     // compilation data

   ValueMap*     _current_map;     // value map of current block

   ValueMapArray _value_maps;      // list of value maps for all blocks

   ValueSet      _processed_values;  // marker for instructions that were already processed

   bool          _has_substitutions; // set to true when substitutions must be resolved

  public:

   // accessors

   Compilation*  compilation() const              { return _compilation; }

   ValueMap*     current_map()                    { return _current_map; }

   ValueMap*     value_map_of(BlockBegin* block)  { return _value_maps.at(block->linear_scan_number()); }

   void          set_value_map_of(BlockBegin* block, ValueMap* map)   { assert(value_map_of(block) == NULL, ""); _value_maps.at_put(block->linear_scan_number(), map); }

   bool          is_processed(Value v)            { return _processed_values.contains(v); }

   void          set_processed(Value v)           { _processed_values.put(v); }

   // implementation for abstract methods of ValueNumberingVisitor

   void          kill_memory()                                 { current_map()->kill_memory(); }

   void          kill_field(ciField* field, bool all_offsets)  { current_map()->kill_field(field, all_offsets); }

   void          kill_array(ValueType* type)                   { current_map()->kill_array(type); }

   // main entry point that performs global value numbering

   GlobalValueNumbering(IR* ir);

   void          substitute(Instruction* instr);  // substitute instruction if it is contained in current value map

 };

 #endif // SHARE_VM_C1_C1_VALUEMAP_HPP