debug names for mode(SI) et al

[DJ Delorie]

Is there any reason why the SImode et al types do not have debug
names?  If you use them in __attribute__((mode(SImode))) (or whatever,
esp vector modes like V4SI), gdb doesn't have enough type information
to display the type, and ends up printing "__unknown__".

How about "__gcc_SImode" or "__intSI" or something like that?

--- c-common.c ---
  /* Define both `signed char' and `unsigned char'.  */
  record_builtin_type (RID_MAX, "signed char", signed_char_type_node);
  record_builtin_type (RID_MAX, "unsigned char", unsigned_char_type_node);

  /* These are types that type_for_size and type_for_mode use.  */
  pushdecl (build_decl (TYPE_DECL, NULL_TREE, intQI_type_node));
  pushdecl (build_decl (TYPE_DECL, NULL_TREE, intHI_type_node));
  pushdecl (build_decl (TYPE_DECL, NULL_TREE, intSI_type_node));
  pushdecl (build_decl (TYPE_DECL, NULL_TREE, intDI_type_node));
#if HOST_BITS_PER_WIDE_INT >= 64
  pushdecl (build_decl (TYPE_DECL, get_identifier ("__int128_t"), intTI_type_node));
#endif
  pushdecl (build_decl (TYPE_DECL, NULL_TREE, unsigned_intQI_type_node));
  pushdecl (build_decl (TYPE_DECL, NULL_TREE, unsigned_intHI_type_node));
  pushdecl (build_decl (TYPE_DECL, NULL_TREE, unsigned_intSI_type_node));
  pushdecl (build_decl (TYPE_DECL, NULL_TREE, unsigned_intDI_type_node));
#if HOST_BITS_PER_WIDE_INT >= 64
  pushdecl (build_decl (TYPE_DECL, get_identifier ("__uint128_t"), unsigned_intTI_type_node));
#endif