gcc/eh-common.h

   1 /* Copyright (C) 1997 Free Software Foundation, Inc.
   2    This file is part of GNU CC.  */
   3
   4 /* This file contains the structures required for the language
   5    independant exception handling model. Both the static compiler and
   6    the runtime library share this file. */
   7
   8 /* The runtime flag flag_new_exceptions is used to determine whether the
   9    compiler supports the new runtime typechecking mechanism or not. Under
  10    the new model, runtime info is contained in the exception table, and
  11    the __throw() library routine determines which handler to call based
  12    on the results of a call to a matching function provided by the expcetion
  13    thrower.  Otherwise the old scheme of calling any handler which matches
  14    an exception range is used, and the handler is responsible for all
  15    checking of runtime conditions. If the handler wasn't suppose to
  16    get the exception, it performs a re-throw. */
  17
  18
  19 /* The handler_label field MUST be the first field in this structure. The
  20    __throw()  library routine expects uses __eh_stub() from except.c, which
  21    simply dereferences the context pointer to get the handler.
  22    The routine get_dynamic_handler_chain() also has a dependancy on
  23    the location of 'dynamic_handler_chain'. If its location is changed,
  24    that routine must be modified as well. */
  25
  26 struct eh_context
  27 {
  28   void *handler_label;
  29   void **dynamic_handler_chain;
  30   /* This is language dependent part of the eh context. */
  31   void *info;
  32   /* This is used to remember where we threw for re-throws */
  33   void *table_index;  /* address of exception table entry to rethrow from */
  34 };
  35
  36 #ifndef EH_TABLE_LOOKUP
  37
  38 typedef struct old_exception_table
  39 {
  40   void *start_region;
  41   void *end_region;
  42   void *exception_handler;
  43 } old_exception_table;
  44
  45 typedef struct exception_table
  46 {
  47   void *start_region;
  48   void *end_region;
  49   void *exception_handler;
  50   void *match_info;              /* runtime type info */
  51 } exception_table;
  52
  53
  54 /* The language identifying portion of an exception table */
  55
  56 typedef struct exception_lang_info
  57 {
  58   short language;
  59   short version;
  60 } exception_lang_info;
  61
  62 /* This value in the first field of the exception descriptor
  63    identifies the descriptor as the new model format. This value would never
  64    be present in this location under the old model */
  65
  66 #define NEW_EH_RUNTIME  ((void *) -2)
  67
  68 /* Each function has an exception_descriptor which contains the
  69    language info, and a table of exception ranges and handlers */
  70
  71 typedef struct exception_descriptor
  72 {
  73   void *runtime_id_field;
  74   exception_lang_info lang;
  75   exception_table table[1];
  76 } exception_descriptor;
  77
  78
  79 /* A pointer to a matching function is initialized at runtime by the
  80    specific language if run-time exceptions are supported.
  81    The function takes 3 parameters
  82     1 - runtime exception that has been thrown info. (__eh_info *)
  83     2 - Match info pointer from the region being considered (void *)
  84     3 - exception table region is in (exception descriptor *)
  85 */
  86
  87 typedef void * (*__eh_matcher)          PROTO ((void *, void *, void *));
  88
  89 /* This value is to be checked as a 'match all' case in the runtime field. */
  90
  91 #define CATCH_ALL_TYPE   ((void *) -1)
  92
  93 /* This is the runtime exception information. This forms the minimum required
  94    information for an exception info pointer in an eh_context structure. */
  95
  96
  97 typedef struct __eh_info
  98 {
  99   __eh_matcher match_function;
 100   short language;
 101   short version;
 102 } __eh_info;
 103
 104 /* Convienient language codes for ID the originating language. Similar
 105    to the codes in dwarf2.h. */
 106
 107 enum exception_source_language
 108   {
 109     EH_LANG_C89 = 0x0001,
 110     EH_LANG_C = 0x0002,
 111     EH_LANG_Ada83 = 0x0003,
 112     EH_LANG_C_plus_plus = 0x0004,
 113     EH_LANG_Cobol74 = 0x0005,
 114     EH_LANG_Cobol85 = 0x0006,
 115     EH_LANG_Fortran77 = 0x0007,
 116     EH_LANG_Fortran90 = 0x0008,
 117     EH_LANG_Pascal83 = 0x0009,
 118     EH_LANG_Modula2 = 0x000a,
 119     EH_LANG_Java = 0x000b,
 120     EH_LANG_Mips_Assembler = 0x8001
 121   };
 122
 123 #endif  /* EH_TABLE_LOOKUP */
 124
 125