1 /*

     2  * Copyright (c) 1998, 2016, Oracle and/or its affiliates. All rights reserved.

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

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP

    26 #define SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP

    27 

    28 #include "memory/allocation.hpp"

    29 #include "oops/method.hpp"

    30 #include "utilities/align.hpp"

    31 

    32 // A HandlerTableEntry describes an individual entry of a subtable

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

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

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

    36 // handler corresponding to the (interpreted) exception handler

    37 // starting at bci.

    38 //

    39 // The first HandlerTableEntry of each subtable holds the length

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

    41 // subtable entries w/o header).

    42 

    43 class HandlerTableEntry {

    44  private:

    45   int _bci;

    46   int _pco;

    47   int _scope_depth;

    48 

    49  public:

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

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

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

    53     _bci = bci;

    54     _pco = pco;

    55     _scope_depth = scope_depth;

    56   }

    57 

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

    59   int bci() const { return _bci; }

    60   int pco() const { return _pco; }

    61   int scope_depth() const { return _scope_depth; }

    62 };

    63 

    64 

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

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

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

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

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

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

    71 // carded.

    72 //

    73 // Structure of the table:

    74 //

    75 // table    = { subtable }.

    76 // subtable = header entry { entry }.

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

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

    79 //

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

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

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

    83 // modified.

    84 

    85 class nmethod;

    86 class ExceptionHandlerTable VALUE_OBJ_CLASS_SPEC {

    87  private:

    88   HandlerTableEntry* _table;    // the table

    89   int                _length;   // the current length of the table

    90   int                _size;     // the number of allocated entries

    91   ReallocMark        _nesting;  // assertion check for reallocations

    92 

    93  public:

    94   // add the entry & grow the table if needed

    95   void add_entry(HandlerTableEntry entry);

    96   HandlerTableEntry* subtable_for(int catch_pco) const;

    97 

    98   // (compile-time) construction within compiler

    99   ExceptionHandlerTable(int initial_size = 8);

   100 

   101   // (run-time) construction from nmethod

   102   ExceptionHandlerTable(const CompiledMethod* nm);

   103 

   104   // (compile-time) add entries

   105   void add_subtable(

   106     int                 catch_pco, // the pc offset for the CatchNode

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

   108     GrowableArray<intptr_t>* scope_depths_from_top_scope,

   109                                            // if representing exception handlers in multiple

   110                                            // inlined scopes, indicates which scope relative to

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

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

   113                                            // innermost scope

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

   115   );

   116 

   117   // nmethod support

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

   119   void copy_to(CompiledMethod* nm);

   120   void copy_bytes_to(address addr);

   121 

   122   // lookup

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

   124 

   125   // debugging

   126   void print_subtable(HandlerTableEntry* t) const;

   127   void print() const;

   128   void print_subtable_for(int catch_pco) const;

   129 };

   130 

   131 

   132 // ----------------------------------------------------------------------------

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

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

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

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

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

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

   139 

   140 // Use 32-bit representation for offsets

   141 typedef  uint              implicit_null_entry;

   142 

   143 class ImplicitExceptionTable VALUE_OBJ_CLASS_SPEC {

   144   uint _size;

   145   uint _len;

   146   implicit_null_entry *_data;

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

   148   ReallocMark          _nesting;  // assertion check for reallocations

   149 public:

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

   151   // (run-time) construction from nmethod

   152   ImplicitExceptionTable( const nmethod *nm );

   153 

   154   void set_size( uint size );

   155   void append( uint exec_off, uint cont_off );

   156   uint at( uint exec_off ) const;

   157 

   158   uint len() const { return _len; }

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

   160 

   161   void copy_to(nmethod* nm);

   162   void print(address base) const;

   163   void verify(nmethod *nm) const;

   164 };

   165 

   166 #endif // SHARE_VM_CODE_EXCEPTIONHANDLERTABLE_HPP