Re: [RFA/dwarf-2] Avoid unnecessary subrange_type (3/3)

[Joel Brobecker <brobecker at gnat dot com>]

> 1) Why do the affected types look like subrange types to begin with?  Why
>    do they have a TREE_TYPE?

Unfortunately, this is a bit beyond my knowledge of GCC. It looked
deliberate, though, when I looked at what stabs look like for
base types (base types are defined as subrange types of themselves),
so I didn't push the issue further. I'll try to investigate a bit
further on my side, but sure would appreciate it if somebody else
on this list already knew the answer (I work mostly on the debugger,
I don't know GCC that well yet).

> 2) Why not just compare type_name == subtype_name?
>    Identifiers are unique.

Nice! I didn't know that. I'll get rid of strcmp. The new code
looks like this (this is nicer):

  if (TREE_CODE (type) == TREE_CODE (subtype)
      && int_size_in_bytes (type) == int_size_in_bytes (subtype)
      && TYPE_MIN_VALUE (type) != NULL
      && TYPE_MIN_VALUE (subtype) != NULL
      && tree_int_cst_equal (TYPE_MIN_VALUE (type), TYPE_MIN_VALUE (subtype))
      && TYPE_MAX_VALUE (type) != NULL
      && TYPE_MAX_VALUE (subtype) != NULL
      && tree_int_cst_equal (TYPE_MAX_VALUE (type), TYPE_MAX_VALUE (subtype)))
    {
      /* The type and its subtype have the same representation.  If in
         addition the two types also have the same name, then the given
         type is not a subrange type, but rather a plain base type.  */
      tree type_name = TYPE_NAME (type);
      tree subtype_name = TYPE_NAME (subtype);
                   
      if (type_name != NULL && TREE_CODE (type_name) == TYPE_DECL)
        type_name = DECL_NAME (type_name);

      if (subtype_name != NULL && TREE_CODE (subtype_name) == TYPE_DECL)
        subtype_name = DECL_NAME (subtype_name);

      if (type_name == subtype_name)
        return false;
    }

Cheers,
-- 
Joel