gcc/eh-common.h

   1 /* EH stuff
   2    Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 This program is free software; you can redistribute it and/or modify it
   7 under the terms of the GNU General Public License as published by the
   8 Free Software Foundation; either version 2, or (at your option) any
   9 later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20
  21 /* This file contains the structures required for the language
  22    independant exception handling model. Both the static compiler and
  23    the runtime library share this file. */
  24
  25 /* The runtime flag flag_new_exceptions is used to determine whether the
  26    compiler supports the new runtime typechecking mechanism or not. Under
  27    the new model, runtime info is contained in the exception table, and
  28    the __throw() library routine determines which handler to call based
  29    on the results of a call to a matching function provided by the expcetion
  30    thrower.  Otherwise the old scheme of calling any handler which matches
  31    an exception range is used, and the handler is responsible for all
  32    checking of runtime conditions. If the handler wasn't suppose to
  33    get the exception, it performs a re-throw. */
  34
  35
  36 /* The handler_label field MUST be the first field in this structure. The
  37    __throw()  library routine expects uses __eh_stub() from except.c, which
  38    simply dereferences the context pointer to get the handler.
  39    The routine get_dynamic_handler_chain() also has a dependancy on
  40    the location of 'dynamic_handler_chain'. If its location is changed,
  41    that routine must be modified as well. */
  42
  43 struct eh_context
  44 {
  45   void *handler_label;
  46   void **dynamic_handler_chain;
  47   /* This is language dependent part of the eh context. */
  48   void *info;
  49   /* This is used to remember where we threw for re-throws */
  50   void *table_index;  /* address of exception table entry to rethrow from */
  51 };
  52
  53 #ifndef EH_TABLE_LOOKUP
  54
  55 typedef struct old_exception_table
  56 {
  57   void *start_region;
  58   void *end_region;
  59   void *exception_handler;
  60 } old_exception_table;
  61
  62 typedef struct exception_table
  63 {
  64   void *start_region;
  65   void *end_region;
  66   void *exception_handler;
  67   void *match_info;              /* runtime type info */
  68 } exception_table;
  69
  70
  71 /* The language identifying portion of an exception table */
  72
  73 typedef struct exception_lang_info
  74 {
  75   short language;
  76   short version;
  77 } exception_lang_info;
  78
  79 /* This value in the first field of the exception descriptor
  80    identifies the descriptor as the new model format. This value would never
  81    be present in this location under the old model */
  82
  83 #define NEW_EH_RUNTIME  ((void *) -2)
  84
  85 /* Each function has an exception_descriptor which contains the
  86    language info, and a table of exception ranges and handlers */
  87
  88 typedef struct exception_descriptor
  89 {
  90   void *runtime_id_field;
  91   exception_lang_info lang;
  92   exception_table table[1];
  93 } exception_descriptor;
  94
  95 struct __eh_info; /* forward declaration */
  96
  97 /* A pointer to a matching function is initialized at runtime by the
  98    specific language if run-time exceptions are supported.
  99    The function takes 3 parameters
 100     1 - runtime exception that has been thrown info. (__eh_info *)
 101     2 - Match info pointer from the region being considered (void *)
 102     3 - exception table region is in (exception descriptor *)
 103 */
 104
 105 typedef void * (*__eh_matcher)  PARAMS ((struct __eh_info *, void *,
 106                                          struct exception_descriptor *));
 107
 108 /* This value is to be checked as a 'match all' case in the runtime field. */
 109
 110 #define CATCH_ALL_TYPE   ((void *) -1)
 111
 112 /* This is the runtime exception information. This forms the minimum required
 113    information for an exception info pointer in an eh_context structure. */
 114
 115
 116 typedef struct __eh_info
 117 {
 118   __eh_matcher match_function;
 119   short language;
 120   short version;
 121 } __eh_info;
 122
 123 /* Convienient language codes for ID the originating language. Similar
 124    to the codes in dwarf2.h. */
 125
 126 enum exception_source_language
 127   {
 128     EH_LANG_C89 = 0x0001,
 129     EH_LANG_C = 0x0002,
 130     EH_LANG_Ada83 = 0x0003,
 131     EH_LANG_C_plus_plus = 0x0004,
 132     EH_LANG_Cobol74 = 0x0005,
 133     EH_LANG_Cobol85 = 0x0006,
 134     EH_LANG_Fortran77 = 0x0007,
 135     EH_LANG_Fortran90 = 0x0008,
 136     EH_LANG_Pascal83 = 0x0009,
 137     EH_LANG_Modula2 = 0x000a,
 138     EH_LANG_Java = 0x000b,
 139     EH_LANG_Mips_Assembler = 0x8001
 140   };
 141
 142 #endif  /* EH_TABLE_LOOKUP */
 143
 144