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

 *

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 * published by the Free Software Foundation.

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 * 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.

 *

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#ifndef SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP

#define SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP

#include "memory/allocation.hpp"

// A HandlerTableEntry describes an individual entry of a subtable

// of ExceptionHandlerTable. An entry consists of a pair(bci, pco),

// where bci is the exception handler bci, and pco is the pc offset

// relative to the nmethod code start for the compiled exception

// handler corresponding to the (interpreted) exception handler

// starting at bci.

//

// The first HandlerTableEntry of each subtable holds the length

// and catch_pco for the subtable (the length is the number of

// subtable entries w/o header).

class HandlerTableEntry {

 private:

  int _bci;

  int _pco;

  int _scope_depth;

 public:

  HandlerTableEntry(int bci, int pco, int scope_depth) {

    assert( 0 <= pco, "pco must be positive");

    assert( 0 <= scope_depth, "scope_depth must be positive");

    _bci = bci;

    _pco = pco;

    _scope_depth = scope_depth;

  }

  int len() const { return _bci; } // for entry at subtable begin

  int bci() const { return _bci; }

  int pco() const { return _pco; }

  int scope_depth() const { return _scope_depth; }

};

// An ExceptionHandlerTable is an abstraction over a list of subtables

// of exception handlers for CatchNodes. Each subtable has a one-entry

// header holding length and catch_pco of the subtable, followed

// by 'length' entries for each exception handler that can be reached

// from the corresponding CatchNode. The catch_pco is the pc offset of

// the CatchNode in the corresponding nmethod. Empty subtables are dis-

// carded.

//

// Structure of the table:

//

// table    = { subtable }.

// subtable = header entry { entry }.

// header   = a pair (number of subtable entries, catch pc offset, [unused])

// entry    = a pair (handler bci, handler pc offset, scope depth)

//

// An ExceptionHandlerTable can be created from scratch, in which case

// it is possible to add subtables. It can also be created from an

// nmethod (for lookup purposes) in which case the table cannot be

// modified.

class nmethod;

class ExceptionHandlerTable VALUE_OBJ_CLASS_SPEC {

 private:

  HandlerTableEntry* _table;    // the table

  int                _length;   // the current length of the table

  int                _size;     // the number of allocated entries

  ReallocMark        _nesting;  // assertion check for reallocations

  // add the entry & grow the table if needed

  void add_entry(HandlerTableEntry entry);

  HandlerTableEntry* subtable_for(int catch_pco) const;

 public:

  // (compile-time) construction within compiler

  ExceptionHandlerTable(int initial_size = 8);

  // (run-time) construction from nmethod

  ExceptionHandlerTable(const nmethod* nm);

  // (compile-time) add entries

  void add_subtable(

    int                 catch_pco, // the pc offset for the CatchNode

    GrowableArray<intptr_t>* handler_bcis, // the exception handler entry point bcis

    GrowableArray<intptr_t>* scope_depths_from_top_scope,

                                           // if representing exception handlers in multiple

                                           // inlined scopes, indicates which scope relative to

                                           // the youngest/innermost one in which we are performing

                                           // the lookup; zero (or null GrowableArray) indicates

                                           // innermost scope

    GrowableArray<intptr_t>* handler_pcos  // pc offsets for the compiled handlers

  );

  // nmethod support

  int  size_in_bytes() const { return round_to(_length * sizeof(HandlerTableEntry), oopSize); }

  void copy_to(nmethod* nm);

  // lookup

  HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const;

  // debugging

  void print_subtable(HandlerTableEntry* t) const;

  void print() const;

  void print_subtable_for(int catch_pco) const;

};

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

// Implicit null exception tables.  Maps an exception PC offset to a

// continuation PC offset.  During construction it's a variable sized

// array with a max size and current length.  When stored inside an

// nmethod a zero length table takes no space.  This is detected by

// nul_chk_table_size() == 0.  Otherwise the table has a length word

// followed by pairs of <excp-offset, const-offset>.

// Use 32-bit representation for offsets

typedef  uint              implicit_null_entry;

class ImplicitExceptionTable VALUE_OBJ_CLASS_SPEC {

  uint _size;

  uint _len;

  implicit_null_entry *_data;

  implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; }

  ReallocMark          _nesting;  // assertion check for reallocations

public:

  ImplicitExceptionTable( ) :  _data(0), _size(0), _len(0) { }

  // (run-time) construction from nmethod

  ImplicitExceptionTable( const nmethod *nm );

  void set_size( uint size );

  void append( uint exec_off, uint cont_off );

  uint at( uint exec_off ) const;

  uint len() const { return _len; }

  int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * sizeof(implicit_null_entry)); }

  void copy_to(nmethod* nm);

  void print(address base) const;

  void verify(nmethod *nm) const;

};

#endif // SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP