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 /*

  * Copyright (c) 1998, 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

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  */

 #ifndef SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP

 #define SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP

 #include "memory/allocation.hpp"

 #include "oops/method.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