gcc/eh-common.h

   1 /* EH stuff
   2    Copyright (C) 1997, 1998 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
  96 /* A pointer to a matching function is initialized at runtime by the
  97    specific language if run-time exceptions are supported.
  98    The function takes 3 parameters
  99     1 - runtime exception that has been thrown info. (__eh_info *)
 100     2 - Match info pointer from the region being considered (void *)
 101     3 - exception table region is in (exception descriptor *)
 102 */
 103
 104 typedef void * (*__eh_matcher)          PROTO ((void *, void *, void *));
 105
 106 /* This value is to be checked as a 'match all' case in the runtime field. */
 107
 108 #define CATCH_ALL_TYPE   ((void *) -1)
 109
 110 /* This is the runtime exception information. This forms the minimum required
 111    information for an exception info pointer in an eh_context structure. */
 112
 113
 114 typedef struct __eh_info
 115 {
 116   __eh_matcher match_function;
 117   short language;
 118   short version;
 119 } __eh_info;
 120
 121 /* Convienient language codes for ID the originating language. Similar
 122    to the codes in dwarf2.h. */
 123
 124 enum exception_source_language
 125   {
 126     EH_LANG_C89 = 0x0001,
 127     EH_LANG_C = 0x0002,
 128     EH_LANG_Ada83 = 0x0003,
 129     EH_LANG_C_plus_plus = 0x0004,
 130     EH_LANG_Cobol74 = 0x0005,
 131     EH_LANG_Cobol85 = 0x0006,
 132     EH_LANG_Fortran77 = 0x0007,
 133     EH_LANG_Fortran90 = 0x0008,
 134     EH_LANG_Pascal83 = 0x0009,
 135     EH_LANG_Modula2 = 0x000a,
 136     EH_LANG_Java = 0x000b,
 137     EH_LANG_Mips_Assembler = 0x8001
 138   };
 139
 140 #endif  /* EH_TABLE_LOOKUP */
 141
 142